The prevention of sexual violence in school settings with adolescents: A study protocol for the cluster randomized trial of the SUN (Stand Up Now against sexual violence) Program

The prevention of sexual violence in school settings with adolescents: A study protocol for the cluster randomized trial of the SUN (Stand Up Now against sexual violence) Program | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Study protocol The prevention of sexual violence in school settings with adolescents: A study protocol for the cluster randomized trial of the SUN (Stand Up Now against sexual violence) Program Eunice Carmo, Nélio Brazão, Patrício Costa, Bárbara Moreira, Joana Carvalho This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7924931/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Sexual violence (SV) is a global public health issue that may arise during adolescence. This project aims to develop, deliver, and assess the efficacy of a new SV bystander prevention program for adolescents: the SUN (Stand Up Now against sexual violence) Program. This manualized bystander program, specifically targeting SV, will be implemented by psychologists in Portuguese schools. The SUN combines psychoeducation with skills training exercises, targeting social norms, attitudes, emotions, and behaviors. Program contents include sexual and reproductive rights, SV, sexual consent, bystander attitudes and behaviors, and empathy. Methods This mixed-method study will involve a pragmatic parallel-arm cluster randomized controlled trial, conducted with the following goals: to assess the program’s efficacy regarding bystander attitudes and behaviors, SV myths, sexism, and empathy; to examine the maintenance of changes three, six, and nine months after the program’s completion; to assess mechanisms of change (i.e., to test whether the reduction of SV myths and sexism and the increase in empathy will predict increases in bystander attitudes and behaviors); to investigate whether age, gender, sexual orientation, and personal history of victimization will influence participants’ responsivity to the program; to assess acceptability and feasibility. The sample will include adolescents from high schools in the North and Centre of Portugal, enrolled in 10th and 11th grades. Participants will be assessed at five time-points using self-report questionnaires and focus groups will be conducted to gather their perceptions regarding the Program. Discussion This will be the first primary prevention program for SV to be assessed in a cluster randomized trial in Portugal, and one of the first to do so in Europe, particularly using a bystander approach. Trial Registration This trial was prospectively registered with ClinicalTrials.gov (Identifier NCT06830278 Registered on 17 February 2025). Adolescents Bystanders High School Primary Prevention Protocol Sexual Violence Figures Figure 1 Introduction Sexual violence (SV) is a global public health issue that often affects adolescents ( 1 – 5 ). A public health approach to SV prevention requires investment in primary prevention strategies that engage individuals from the general population to address SV before it occurs ( 4 , 6 ). Schools bring together large and diverse groups of young people and are naturally equipped for fostering knowledge, prosocial attitudes, and skills, making them an effective setting for violence prevention ( 7 , 8 ). Accordingly, many research groups have developed school-based primary prevention programs for SV, as recommended by international guidelines ( 9 – 18 ). Nonetheless, researchers have highlighted relevant caveats that should not be overlooked. One urgent issue is the regional imbalance in the implementation of evidence-based programs, as 73% of those have been conducted in the U.S.A. ( 19 , 20 ). Moreover, most adolescent prevention programs have addressed SV in the context of dating violence, which may be ineffective, given that previous reviews found non-significant effects on SV outcomes in such programs ( 20 – 22 ). In line with these results, there has been a gradual shift in focus, with more recent programs approaching SV specifically ( 20 ). This is mainly due to an investment in bystander programs, which aim to enable individuals to mitigate the risk of SV by accurately identifying such situations and engaging in preventive actions. These may include confronting a person who is exploiting someone unable to provide consent, offering support to a victim, or reporting a violent incident ( 23 – 27 ). In short, the bystander approach centers primary prevention of SV on the public health argument, involving every member of every community in its prevention ( 28 ). A recent review of bystander SV prevention programs for youth and adults in schools and other contexts found that most increased bystander behaviors and decreased the acceptance of myths, as well as sexually coercive behaviors ( 27 ). Besides, these programs also tend to address SV risk and protective factors, by including content on potential mediators (e.g., empathy) and considering potential moderators (e.g., prior victimization) ( 20 ). In line with this, the present study draws on a bystander approach and prior evidence that empathy is a protective factor, while SV myths and sexism are risk factors for SV ( 29 – 31 ). Current Study This protocol describes the research project which aims to assess the efficacy of a new SV prevention program for adolescents: the SUN (Stand Up Now against sexual violence) Program, applied in Portugal. This will be an efficacy trial, as it will constitute the first evaluation of the program using a CRT design under conditions approximating an ideal implementation: a standardized manualized intervention, no concurrent programs, specialized external facilitators (i.e., not delivered by school staff), and objective outcomes. Nonetheless, some pragmatic elements will be present (such as broad inclusion criteria, the use of "treatment as usual" in control groups, and the absence of double blinding) reflecting the real-world constraints of implementing a universal primary prevention program in school settings ( 32 , 33 ). Method Study Design, Aims, and Hypotheses This project will aim to develop, implement, and evaluate the efficacy of a new bystander primary prevention program for SV targeting high school adolescents in Portugal: the SUN (Stand Up Now against sexual violence) Program. The study will follow the CONSORT 2010 statement: extension to cluster randomized trials ( 34 ) and the Standards of Evidence for Efficacy, Effectiveness, and Scale-up Research in Prevention Science ( 35 ). Additionally, the trial has been registered as a cluster randomized trial (CRT) at ClinicalTrials.gov (Identifier: NCT06830278; Registered on 17 February 2025) ( 36 ). This will be a mixed-method, pragmatic, parallel-arm CRT (please see Fig. 1 for the Study Flow Diagram) with the following aims: 1) to assess the program’s efficacy in increasing bystander attitudes, behaviors, and empathy, and reducing SV myths and sexism; 2) to examine whether changes are maintained at three, six, and nine months follow-up; 3) to explore mechanisms of change by testing whether reduced SV myths and sexism and increased empathy predict improvements in bystander outcomes; 4) to investigate whether age, gender, sexual orientation, or victimization history affect responsiveness; and 5) to assess the program’s acceptability and feasibility. Based on the theoretical framework, the following hypotheses will be developed: 1) Participants in the experimental group will show greater increases in bystander attitudes, behaviors, and empathy, and greater reductions in SV myths and sexism than the control group; 2) In the experimental group, reductions in SV myths and sexism and increases in empathy will predict improvements in bystander attitudes and behaviors; 3) Younger participants, those identifying with gender or sexual minority groups, and those with victimization histories will show greater responsiveness to the intervention. The randomized trial will have a longitudinal design with five time-points: baseline (one week before the first session of the SUN), post-test (one week after the last session of the SUN), three-month, six-month, and nine-month follow-up assessments. These time-points will balance the need to monitor long-term change with considerations of feasibility and participant acceptability. Ideally, a longer follow-up period (e.g., 12 to 18 months) would be included; however, evidence from studies with similar samples and outcomes that observed significant effects with comparable follow-up durations supports the adequacy of this approach ( 35 , 37 , 38 ). Procedures to minimize testing effects will include randomization, control groups, and statistical controls (i.e., statistical tests will be used to compare relevant psychological dimensions between groups; in case significant differences are found, these dimensions will be included as covariates in statistical analyses) ( 39 – 41 ). [Insert Fig. 1 about here] Setting and Sample Eligible schools will include public, vocational, and private institutions in Northern and Central Portugal with at least two 10th or 11th grade classes and Portuguese-speaking students. Schools will also have to offer appropriate infrastructure and scheduling for assessments and sessions. Age will not be an exclusion criterion, given variability across regions and classes (typically 14–19 years). The only individual exclusion criteria will be serious developmental, mental, or physical health conditions that prevented participation, as reported by caregivers or school staff. Adolescents were selected based on epidemiological evidence indicating high SV prevalence in this group ( 5 , 42 ); the differences in sexual victimization and perpetration in adolescence in comparison to childhood or adulthood ( 43 , 44 ); and the risk of victimization and perpetration trajectories persisting into adulthood ( 29 , 31 , 45 , 46 ). Grades 10 and 11 were chosen to increase adherence to follow-ups, minimizing dropout risk before high school completion in 12th grade. Sample Size Estimation and Statistical Analysis Plan A priori sample size estimation accounted for the cluster randomized trial (CRT) design, in which classes are the unit of randomization. The trial includes two parallel arms (intervention vs. control) and five assessment points (baseline, post-test, 3-, 6-, and 9-month follow-ups). Sample Size Estimation The base sample size was calculated in G*Power 3.1 ( 47 ) for a two-tailed t-test comparing two independent means, with α = .05, power = .80, and a standardized effect size of d = 0.30, consistent with previous school-based bystander and prevention programs ( 37 , 48 , 49 ). This analysis indicated that 352 participants (176 per group) are required under individual randomization. Because randomization occurs at the class level, the sample was inflated using the design effect (DE) formula: DE = 1 + ( m − 1) × ICC Assuming an average class size of m = 15 students and an intraclass correlation coefficient (ICC) = 0.03, typical for psychosocial outcomes in educational settings ( 35 , 50 ), the design effect equals 1.42. Adjusting for clustering increases the total required sample to approximately 500 students (≈ 250 per arm), corresponding to 34 classes (17 per arm). To accommodate 20% expected attrition over the 9-month follow-up ( 48 , 51 ), the final recruitment target is approximately 600 students (≈ 40 classes, 20 per arm). This sample size provides a minimum of 80% power to detect small-to-moderate effects and is sufficient for planned moderation and mediation analyses. If cluster sizes vary substantially, the design effect will be corrected using the coefficient of variation (CV) of class size ( 50 ). For the mechanism-of-change analyses, an a priori RMSEA-based power analysis (power4SEM; ( 52 )) indicated that N ≈ 550 achieves 80% power for detecting model fit differences (testing RMSEA₀ = .05 vs. RMSEA₁ = .08, α = .05). The planned CRT sample (≈ 600 participants) therefore ensures sufficient power for longitudinal structural equation modeling (SEM). Recruitment and Randomization Schools that respond to the project invitation will participate in preliminary meetings where the research team will explain the program structure, consent and assent procedures, the randomization process, and assessment protocol. Schools will then be asked to evaluate their interest and feasibility conditions for participation, considering aspects such as the number of available classes, student numbers per class, gender distribution, and schedule compatibility. Once selected, each school will designate the specific classes to be included in the study. Subsequently, presentation sessions will be held with students and teachers from the selected classes to reiterate the information previously shared. In this project, the unit of randomization (i.e., the cluster) will be the class, so the study will include at least a control and experimental group per school. This decision was ethically and pragmatically driven, considering the balance of efforts and benefits between groups and feasibility conditions. Several procedures will be adopted to minimize contamination across conditions: school staff involved in the experimental groups will not work with control groups and vice versa; sessions for each group will be scheduled at different times and on different days to reduce interaction; control and experimental groups will use different classrooms; and only facilitators will have access to program materials. Classes will be randomly assigned to either the intervention or control group using block randomization in a 1:1 ratio, performed after baseline assessments via a randomization software tool ( https://www.randomizer.org/ ). Given the pragmatic nature of the trial, neither research staff, school staff, nor participants will be blinded to group allocation ( 34 ). Intervention and Control Group The SUN is a manualized program that integrates psychoeducation with skill-building exercises and targets social norms, attitudes, emotions, and behaviors. The program will comprise ten weekly sessions of 50 to 60 minutes, delivered to mixed-gender groups, mirroring regular class settings to ensure ecological validity and in accordance with the current evidence in the field ( 53 , 54 ). The number of students per class (and session) is expected to vary between 10 and 25. Sessions will be facilitated by two psychologists and SV researchers with training in prevention programs for adolescents and in the implementation of the SUN. Supervision will be provided by the multidisciplinary research team, composed of an Assistant Professor with Habilitation in Forensic Psychology, Sexology, and Experimental Research; an Associate Professor in Research Methods and Statistics; an Assistant Professor in Forensic Psychology; and two PhD candidates specializing in Forensic Psychology. The SUN was designed in accordance with the good practice standards of prevention science ( 35 ), namely the nine characteristics of effective prevention: comprehensive; theory driven; varied teaching methods; sufficient dosage; positive relationships; appropriately timed; socioculturally relevant; outcome evaluation; and well-trained staff ( 55 ). Furthermore, the intervention was informed by best practices identified in prior research and adapted to the Portuguese context, following guidance for comprehensive, multi-session programs targeting mixed-gender groups ( 20 , 24 , 26 , 35 , 54 , 56 , 57 ). Grounded in bystander intervention theory, the SUN will train participants to: 1) understand the different manifestations of SV; 2) challenge social norms associated with tolerance of SV (i.e., SV myths and sexism); 3) recognize support resources for SV situations; 4) use proactive bystander behaviors to reduce SV risk; 5) use reactive bystander behaviors to mitigate SV consequences; and 6) demonstrate empathy for SV victims ( 22 , 27 , 58 , 59 ). For a detailed description of the program sessions, please consult Table 1 . Table 1 The SUN Program: Session Structure Session Session Theme Session Goals Module 1 – Sexual Violence Session 1 Introduction; Sexual and reproductive rights Defining SV Understanding SV as a human rights violation Describing sexual and reproductive rights Session 2 SV: behaviors and contexts Understanding the variety of behaviors classified as SV Identifying the contexts in which SV occurs Session 3 Sexual consent Discussing the concept of sexual consent Distinguishing situations of sexual consent and non-consent Session 4 SV myths Challenging SV myths Session 5 Sexual teen dating violence Reflecting on sexual consent within dating relationships Challenging SV myths in the context of dating violence Reflecting on online SV Module II –Bystander Intervention Session 6 The role of a bystander Understanding the concepts of bystander attitudes and behaviors Identifying proactive and reactive bystander behaviors Session 7 The bystander effect Understanding the bystander effect Identifying obstacles to bystander intervention Learning to use helplines and support resources Session 8 Bystander intervention Distinguishing the 6 D’s of bystander intervention Applying the 6D’s of bystander intervention to a case study Session 9 Empathy Understanding the application of empathy to bystander intervention Discussing victims’ testimonies Training empathic communication Session 10 Summary Applying skills: communication about consent; empathic communication; bystander intervention [Insert Table 1 about here] The control groups will follow their usual school schedule and will not receive any intervention beyond the standard curricular and extracurricular activities. Measures All outcomes will be assessed at the individual level, allowing for participant-level measurement of change while accounting for clustering in the analysis. Primary outcome measures will include: bystander attitudes measured by the Bystander Attitude Scale-Revised (BAS-R) ( 59 ) and bystander behaviors measured by the Bystander Behavior Scale-Revised (BBS-R) ( 59 ). Secondary outcomes measures will include: empathy measured by the Basic Empathy Scale-Adolescents (BES-A) ( 60 ); sexual violence myths measured by sexual violence subscales of the Attitude Toward Dating Violence Scale ( 61 ); sexism measured by the Sexism Detection Scale ( 62 ). Social desirability measured by the Social Desirability scale ( 63 ) will be included as a covariate. The primary outcome measures were selected considering the aim of the SUN: to develop bystander attitudes and behaviors. Secondary outcomes and mechanisms of change (i.e., empathy, SV myths and sexism) were selected according to theory and previous findings ( 20 ). The assessment protocol will start with a sociodemographic survey including school year, age, gender identity, sexual orientation, and personal history of victimization. Glossaries will be included to ensure that participants understand every option available. The survey will end with a list of support resources that participants may wish to use in case of need, such as victim support services ( 64 ). Bystander Attitude Scale-Revised The Bystander Attitude Scale-Revised (modified version) is a self-report survey that measures bystander attitudes using 19 items ( 59 ). This study uses a recent adaptation of this scale into Portuguese for adolescents, using only 13 items (Unpublished data). The Portuguese adaptation revealed three subscales: 1) high risk situations, about scenarios in which the victim faces an imminent threat of SV (6 items, e.g., “Confront a friend who plans to give someone alcohol to get sex.”) 2) proactive opportunities; regarding situations where there is an opportunity to learn about SV (2 items, e.g., “Take a class to learn more about sexual violence and abuse.”); and 3) post-assault interventions, corresponding to attitudes regarding supporting victims and reporting offenders (4 items, e.g., “Report a friend that committed a rape.”). In this survey, participants will be asked to rate how acceptable a behavior is for them (i.e., whether they were favorable to that behavior) on a Likert scale from 1 (not acceptable) to 5 (extremely acceptable). The three-factor structure of the Portuguese adaptation revealed good internal consistency (α = .86 for the total scale; α = .88 for high-risk situations, α = .60 for proactive behaviors and α = .83for post-assault behaviors) (Unpublished data). Bystander Behavior Scale-Revised The Bystander Behavior Scale-Revised (modified version) is a self-report survey similar to the BAS-R but which measures bystander behavior. Items are the same, but participants are asked to report whether they have had those behaviors (scale: “Yes”, “No”, “I wasn’t in that situation”) ( 59 ). In this study, a Portuguese version of the BBS-R undergoing psychometric validation will be used (Unpublished Data). Basic Empathy Scale-Adolescents The Basic Empathy Scale-Adolescents (BES-A) is a 16-item self-report questionnaire for adolescents that evaluates empathy in its affective and cognitive dimensions ( 60 , 65 ). This study will use the Portuguese version, which has a two-factor structure: 1) cognitive empathy subscale (8 items, e.g., “I can often understand how people are feeling even before they tell me”); 2) affective empathy subscale (8 items, e.g., “After being with a friend who is sad about something, I usually feel sad”) ( 60 ). Answers are given according to a five-point scale, ranging from 1 = strongly disagree and 5 = strongly agree. Authors reported that both subscales reached good internal consistency values (α = .80 for affective empathy and α = .85 for cognitive empathy). Both subscales were significantly and positively correlated with measures of social skills and significantly and negatively correlated with measures of aggression ( 60 ). Attitudes Toward Dating Violence Scale The Portuguese adaptation of the Attitudes Toward Dating Violence Scale, a self-report questionnaire regarding dating violence for adolescents will be used to assess SV myths ( 61 , 66 ). This study will use two subscales: the Sexual Violence perpetrated by Men subscale (12 items, e.g., “When boys are very sexually aroused, they cannot avoid having sex”) and the Sexual Violence perpetrated by Women subscale (12 items, e.g., “There is nothing wrong with a girl forcing her boyfriend to kiss her”) ( 61 ). Answers are given according to a five-point Likert scale, ranging from 1 = strongly disagree and 5 = strongly agree. Authors reported that both subscales reached good internal consistency values (α = .80 for Sexual Violence perpetrated by Men and α = .83 for Sexual Violence perpetrated by Women). Sexism Detection Scale The Sexism Detection Scale (DSA) is a self-report questionnaire including 26 items aimed at detecting sexism in adolescents ( 62 , 67 ). The scale includes two subscales: ten items measure benevolent sexism (e.g., Women are, naturally, more patient and tolerant than men.”) and 16 items measure hostile sexism (e.g., “The most adequate place for a woman is at home with her family”) ( 67 ). Answers are given according to a six-point scale, ranging from 1 = strongly disagree and 6 = strongly agree. The two-factor structure of the Portuguese adaptation revealed excellent internal consistency (α = .93; α = .93 for hostile sexism; and α = .85 for benevolent sexism). Social Desirability Scale The EDS-20 (Social Desirability Scale) is a 20-item self-report questionnaire developed to assess social desirability in diverse samples, including adolescents ( 63 ). Items are answered on a dichotomous scale of “Yes” or “No”. An item example would be “Have you ever taken advantage of someone?”. This scale has shown appropriate psychometric properties in several Portuguese samples ( 68 , 69 ). Moderator variables (age, gender, sexual orientation, and personal history of victimization) will only be assessed at baseline, using the sociodemographic survey, and were selected according to the previous literature ( 44 , 70 – 72 ). Research questions regarding the acceptability and feasibility ( 73 ) of the SUN will be gathered via the team’s field notes, and participants’ focus groups. Field notes will include the systematic registration of fidelity to the SUN Manual and perceptions regarding the acceptability and feasibility of procedures. The focus groups will be described in future publications. Statistical Analysis Plan Analyses will follow the intention-to-treat principle. Given the hierarchical and longitudinal structure (time nested within participants, participants nested within classes), intervention effects will be examined using Linear Mixed-Effects Models (LMMs) with random intercepts for clusters and participants, and fixed effects for group, time, and their interaction (group × time). This approach accounts for intra-cluster dependency and individual change trajectories while handling missing data under the Missing at Random (MAR) assumption via Full Information Maximum Likelihood (FIML) estimation ( 74 ). Baseline covariates will be controlled where appropriate. Moderation effects (age, gender, sexual orientation, victimization history) will be evaluated through interaction terms in the LMM framework. To explore mechanisms of change, longitudinal SEM (latent growth and cross-lagged models) will examine whether reductions in sexual violence myths and sexism, and increases in empathy, mediate improvements in bystander attitudes and behaviors over time. Qualitative Analyses and Integration Qualitative data will be analyzed to assess program acceptability, feasibility, and perceived impact. Integration of quantitative and qualitative results will occur at the interpretation stage, following a convergent mixed-methods design, to provide comprehensive insights into program efficacy, mechanisms of change, and contextual factors influencing implementation. Ethical Considerations Ethical approval for this project was granted by the Ethics Committee of the Faculty of Psychology and Education Sciences of the University of Porto (Approval number: Ref.ª 2022/07 − 03). The study follows ethical standards for research with human participants and psychological intervention in this context ( 11 , 64 , 75 – 78 ). All assessments will be conducted by trained psychologists and researchers with experience in victim and offender support, ensuring that any disclosure of violence is managed according to the highest ethical standards. Participants will have access to facilitators or researchers outside the sessions through multiple contact channels. The team will be available to offer psychological support, referrals to specialized services, or assistance in reporting violent situations. Before enrollment, all participants will attend a presentation session outlining the sessions and study procedures, including consent, assent, and assessments. At the end of the session, participants under 18 will receive an assent form and a caregiver consent form; those 18 or older will receive a consent form for themselves. These procedures comply with the schools’ legal requirements. Signed forms will be collected about a week later, allowing time for informed decisions. Discussion This research project aims to develop, deliver, and assess the efficacy of a new bystander primary prevention program for SV targeting high school adolescents in Portugal: the SUN (Stand Up Now against sexual violence) Program. This cluster randomized trial (CRT) has five main goals: 1) assess the program’s efficacy in improving bystander attitudes and behaviors, reducing SV myths and sexism, and increasing empathy; 2) evaluate the durability of these effects at three, six, and nine months follow-up; 3) explore mechanisms of change; 4) examine whether age, gender, sexual orientation, and victimization history moderate the program’s impact; and 5) to assess the program’s acceptability and feasibility. This project presents some limitations. Firstly, due to limited resources, the CRT expected sample size is smaller than in similar U.S.-based trials. However, sample size must be considered within the Portuguese research context. Secondly, recruitment will be limited to schools in the North and Centre of the country, which restricts national representativeness. Nonetheless, recruitment will cover at least two districts and includes various school types. Thirdly, survey data are subject to the usual limitations of self-report, although a social desirability scale will be included to mitigate bias, and focus groups will be used for triangulation. The SUN Program’s CRT is grounded in key premises: a) SV is a global public health concern ( 79 ); b) victimization and perpetration trajectories beginning in adolescence have severe consequences ( 80 ); c) school-based bystander programs are effective ( 20 – 22 , 27 ). This study addresses significant gaps in adolescent SV prevention through a theory-based, methodologically rigorous approach. To our knowledge, the SUN is one of the first SV primary prevention programs evaluated through a CRT in Europe and the first in Portugal. This project is expected to have a meaningful impact on SV prevention among adolescents, raising awareness among students, caregivers, school staff, and the wider community. It aims to demonstrate relevant public health benefits and advance scientific knowledge in SV prevention through the dissemination of findings. Abbreviations BAS-R Bystander Attitude Scale-Revised BBS-R Bystander Behaviour Scale-Revised BES-A Basic Empathy Scale-Adolescents CRT Cluster Randomized Trial CV Coefficient of Variation DSA Sexism Detection Scale EDS-20 Social Desirability Scale FIML Full Information Maximum Likelihood estimation ICC Intraclass Correlation Coefficient LMMs Linear Mixed-Effects Models MAR Missing at Random RMSEA Root Mean Square Error of Approximation SEM Structural Equation Modeling SUN Stand Up Now against sexual violence Program SV Sexual Violence Declarations Authors’ contributions: EC: Conceptualization, Methodology, Software, Resources, Writing – original draft, Writing – review & editing, Visualization, Project administration, Funding acquisition NB: Conceptualization, Methodology, Software, Writing – review & editing, Supervision, Funding acquisition PC: Methodology, Software, Writing – review & editing, Supervision BM: Conceptualization, Methodology, Writing – review & editing, Funding acquisition JC: Conceptualization, Methodology, Writing – review & editing, Supervision, Project administration, Funding acquisition Ethics approval and consent to participate: Ethical approval for this study was obtained from the Ethical Committee of the Faculty of Psychology and Education Sciences of the University of Porto (Approval number: Ref.ª 2022/07-03). Written informed consent will be obtained from all participants and their legal guardians prior to participation. The study will be conducted in accordance with the Declaration of Helsinki and national data protection regulations. Consent for publication: Not Applicable. Availability of data and materials: Not Applicable. Competing interests: The authors declare that they have no competing interests. Funding statement: This study is supported by a PhD Grant from Fundação para a Ciência e Tecnologia (2022.11986.BD) awarded to Eunice Carmo. The study protocol has not undergone peer review as part of the funding process. Acknowledgements: Not Applicable. Trial Registration: This trial was prospectively registered with ClinicalTrials.gov (Identifier: NCT06830278; Registered on 17 February 2025). References Alexander KA, Miller E. Sexual violence: Another public health emergency. JAMA Netw Open. 2022;5(10). Basile KC, DeGue S, Jones K, Freire, KD, Smith J, Raiford SG. JL. STOP SV: A technical package to prevent sexual violence. Atlanta, GA.; 2016. Kuo C, Mathews C, Abrahams N. Chapter 12 - Sexual violence as a global health problem: Current evidence and future directions. In: Orchowski LM, Gidycz CA, editors. Sexual assault risk reduction and resistance. San Diego: Academic; 2018. pp. 291–308. McMahon PM. The public health approach to the prevention of sexual violence. Sex Abuse. 2000;12(1). Ngo QM, Veliz PT, Kusunoki Y, Stein SF, Boyd CJ. Adolescent sexual violence: Prevalence, adolescent risks, and violence characteristics. Prev Med. 2018;116:68–74. DeGue S, Holt MK, Massetti GM, Matjasko JL, Tharp AT, Valle LA. Looking ahead toward community-level strategies to prevent sexual violence. J Women's Health. 2012;21(1):1–3. Farrell AD, Meyer AL, Kung EM, Sullivan TN. Development and evaluation of school-based violence prevention programs. J Clin Child Adolesc Psychol. 2001;30(2). Fagan AA, Catalano RF. What works in youth violence prevention: A review of the literature. Res Social Work Pract. 2013;23(2). Council of Europe. Convention on the protection of children against sexual exploitation and sexual abuse.; 2007. Council of Europe. Convention on preventing and combating violence against women and domestic violence.; 2011. WHO. Ethical and safety recommendations for intervention research on violence against women. Building on lessons from the WHO publication Putting women first: ethical and safety recommendations for research on domestic violence against women. 2016. WHO. INSPIRE: Seven strategies for ending violence against children. 2016. WHO. Preventing intimate partner and sexual violence against women: Taking action and generating evidence. 2010. WHO. RESPECT women: Preventing violence against women. 2019. WHO. Understanding and addressing violence against women: Health consequences. 2012. UNPFA. The evaltuation of comprehensive sexuality education programmes: A focus on the gender and empowerment outcomes. 2015. UNESCO. Sexuality education review and assessment tool (SERAT). 2021. Ligiero D, Hart C, Fulu E, Thomas A, Radford L. What works to prevent sexual violence against children: Evidence review. Together for Girls; 2019. Ellsberg M, Arango DJ, Morton M, Gennari F, Kiplesund S, Contreras M et al. Prevention of violence against women and girls: what does the evidence say? Lancet. 2015;385(9977). Carmo E, Brazão N, Carvalho J. The primary prevention of sexual violence against adolescents in school and community settings: A scoping review. J Sex Res. 2024. Piolanti A, Foran HM. Efficacy of interventions to prevent physical and sexual dating violence among adolescents: A systematic review and meta-analysis. JAMA Pediatr. 2022;176(2). Piolanti A, Jouriles EN, Foran HM. Assessment of psychosocial programs to prevent sexual violence during adolescence: A systematic review and meta-analysis. JAMA Netw Open. 2022;5(11). Banyard V, Waterman E, Edwards K. Bystanders to prevent peer sexual violence: understanding patterns of prosocial behavior over time from early to later adolescence. J Youth Adolesc. 2021;50(10):1982–94. Kovalenko AG, Abraham C, Graham-Rowe E, Levine M, O’Dwyer S. What works in violence prevention among young people? A systematic review of reviews. Trauma Violence Abuse. 2022;23(5). Miller E. Reclaiming gender and power in sexual violence prevention in adolescence. Violence Against Women. 2018;24(15). Katz J, Moore J. Bystander education training for campus sexual assault prevention: An initial meta-analysis. Violence Vict. 2013;28(6):1054–67. Mujal GN, Taylor ME, Fry JL, Gochez-Kerr TH, Weaver NL. A systematic review of bystander interventions for the prevention of sexual violence. Trauma, Violence, & Abuse. 2021;22(2). McMahon S, Postmus J, Koenick RA. Conceptualizing the engaging bystander approach to sexual violence prevention on college campuses. J Coll Student Dev. 2011;52. Basile KC, Rostad WL, Leemis RW, Espelage DL, Davis JP. Protective factors for sexual violence: Understanding how trajectories relate to perpetration in high school. Prev Sci. 2018;19(8):1123–32. Fernández-Fuertes AA, Fernández-Rouco N, Lázaro-Visa S, Gómez-Pérez E. Myths about sexual aggression, sexual assertiveness and sexual violence in adolescent romantic relationships. Int J Environ Res Public Health. 2020;17(23). Ybarra ML, Thompson RE. Predicting the emergence of sexual violence in adolescence. Prev Sci. 2018;19(4):403–15. Marchand E, Stice E, Rohde P, Becker CB. Moving from efficacy to effectiveness trials in prevention research. Behav Res Ther. 2011;49(1):32–41. Loudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ. 2015;350(may08 1):h2147–h. Campbell MK, Piaggio G, Elbourne DR, Altman DG. Consort 2010 statement: extension to cluster randomised trials. BMJ. 2012;345. Gottfredson DC, Cook TD, Gardner FE, Gorman-Smith D, Howe GW, Sandler IN et al. Standards of evidence for efficacy, effectiveness, and scale-up research in prevention science: Next generation. Prevention Science. 2015;16(7). ClinicalTrials.gov. The efficacy of the SUN program in adolescents (SUN)(NCT06830278) Clinical trial registration. U.S. National Library of Medicine.; 2025. Culyba AJ, Fuhrman B, Barker G, Abebe KZ, Miller E. Primary versus secondary prevention effects of a gender-transformative sexual violence prevention program among male youth: A planned secondary analysis of a randomized clinical trial. J interpers Violence. 2023;38:19–20. Orchowski LM, Malone S, Sokolovsky AW, Pearlman DN, Rizzo C, Zlotnick C, et al. Preventing sexual violence among high school students through norms correction and bystander intervention: A school-based cluster trial of Your Voice Your View. J Community Psychol. 2023;51(7):2861–86. Dimitrov DM, Rumrill PD. Jr. Pretest-posttest designs and measurement of change. Work. 2003;20(2):159–65. French DP, Sutton S. Reactivity of measurement in health psychology: How much of a problem is it? What can be done about it? Br J Health Psychol. 2010;15(3):453–68. Jones SMW, Shulman LJ, Richards JE, Ludman EJ. Mechanisms for the testing effect on patient-reported outcomes. Contemp Clin Trials Commun. 2020;18. Marcos V, Seijo D, Montes Á, Arce R. Prevalence and quantification of the effects of sexual harassment victimization of school-aged adolescents. Children. 2024;11(1). Torazzi E, Merelli V, Barbara G, Kustermann A, Marasciuolo L, Collini F et al. Similarity and differences in sexual violence against adolescents and adult women: The need to focus on adolescent victims. J Pediatr Adolesc Gynecol. 2021;34(3). Barbara G, Albertini V, Tagi VM, Maggioni L, Gorio MC, Cattaneo C, et al. Characteristics of sexual violence against adolescent girls: A 10 years' retrospective study of 731 sexually abused adolescents. Int J Women's Health. 2022;14:311–21. Ybarra ML, Petras H. Groups of sexual violence perpetration in a national sample of youth 13–25 years of age. Prev Sci. 2021;22(2). Mumford EA, Liu W, Taylor BG. Longitudinal trajectories of perpetration of adolescent dating abuse in a national sample. Aggressive Behav. 2019;45(3). Faul F, Erdfelder E, Lang A-G, Buchner A. G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39(2):175–91. Coker AL, Bush HM, Brancato CJ, Clear ER, Recktenwald EA. Bystander Program Effectiveness to Reduce Violence Acceptance: RCT in High Schools. J Fam Violence. 2019;34(3):153–64. DeGue S, Niolon PH, Estefan LF, Tracy AJ, Le VD, Vivolo-Kantor AM, et al. Effects of Dating Matters® on Sexual Violence and Sexual Harassment Outcomes among Middle School Youth: a Cluster-Randomized Controlled Trial. Prev Sci. 2021;22(2):175–85. Murray DM, Blistein JL. Methods to reduce the impact of intraclass correlation in group-randomized trials. Eval Rev. 2003;27(1):79–103. Matos MG, Gaspar T, Ferreira M, Simões C. Health Behaviour in School-Aged Children: Portugal 2018 Report. Lisboa: FMH-ULisboa; 2021. Wolf EJ, Harrington KM, Clark SL, Miller MW. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety. Educ Psychol Meas. 2013;76(6):913–34. Elias-Lambert N, Black B, Sharma Y. Middle school youth: satisfaction with and responses to a dating violence and sexual assault prevention program. J School Violence. 2010;9(2). Kettrey HH, Marx RA. Does the gendered approach of bystander programs matter in the prevention of sexual assault among adolescents and college students? A systematic review and meta-analysis. Arch Sex Behav. 2019;48(7). Nation M, Crusto C, Wandersman A, Kumpfer KL, Seybolt D, Morrissey-Kane E, et al. What works in prevention: Principles of effective prevention programs. Am Psychol. 2003;58:6–7. DeGue S, Valle LA, Holt MK, Massetti GM, Matjasko JL, Tharp AT. A systematic review of primary prevention strategies for sexual violence perpetration. Aggress Violent Beh. 2014;19(4):346–62. Moore GF, Audrey S, Barker M, Bond L, Bonell C, Hardeman W et al. Process evaluation of complex interventions: Medical Research Council guidance. BMJ. 2015. Reidy DE, D’Inverno AS, Bogen KW, Swahn MH, Jacobs GM. Masculinity and violence against women from a social-ecological perspective: Implications for prevention. In: Geffner R, White JW, Hamberger LK, Rosenbaum A, Vaughan-Eden V, Vieth VI, editors. Handbook of interpersonal violence and abuse across the lifespan: A project of the National Partnership to End Interpersonal Violence Across the Lifespan (NPEIV). Cham: Springer International Publishing; 2022. pp. 2353–74. McMahon S, Allen CT, Postmus JL, McMahon SM, Peterson NA, Lowe Hoffman M. Measuring bystander attitudes and behavior to prevent sexual violence. J Am Coll Health. 2014;62(1). Anastácio S, Paula V, Luiza N-L, Daniel R, Jolliffe D. The Portuguese version of the Basic Empathy Scale (BES): Dimensionality and measurement invariance in a community adolescent sample. Eur J Dev Psychol. 2016;13(5):614–23. Saavedra RMM, Machado C. Prevenir antes de remediar: Prevenção da violência nos relacionamentos íntimos juvenis. Escola de Psicologia: Universidade do Minho; 2010. Fernandes M, Moreira I, Silva A, Sá M, Veríssimo C, Leitão M. Escala de Detección de Sexismo en Adolescentes: tradução e validação para o contexto português. Revista de Enfermagem Referência, V Série; 2020. Almiro PA, Almeida D, Ferraz AM, Ferreira R, Silvestre MJ, Perdiz C, et al. Escala de Desejabilidade Social de 20 itens (EDS-20). In: Simões MR, Almeida LS, Gonçalves MM, editors. Psicologia Forense: Instrumentos de Avaliação. Lisboa: Pactor/Lidel; 2017. Sharkey JD, Reed LA, Felix ED. Dating and sexual violence research in the schools: Balancing protection of confidentiality with supporting the welfare of survivors. Am J Community Psychol. 2017;60:3–4. Jolliffe D, Farrington DP. Development and validation of the Basic Empathy Scale. J Adolesc. 2006;29(4). Price EL, Byers ES, Belliveau N, Bonner R, Caron B, Doiron D et al. The attitudes towards dating violence scales: Development and initial validation. J Family Violence. 1999;14(4). Recio P, Cuadrado Guirado I, Ramos E. Propiedades psicométricas de la Escala de Detección de Sexismo en Adolecentes (DSA). Psicothema. 2007;19(3):522–8. Nunes C, Paulino M, Simões M. Avaliação da Desejabilidade Social numa amostra de progrenitores em litígio: Estudos de validação da EDS-20. Universidade de Coimbra2024. Marques A, Almiro P. Estudos de validação de duas escalas de avaliação da desejabilidade social, EDS-20 e DESCA, numa amostra forense. Repositório da Universidade de Lisboa.; 2016. Foshee VA, Bauman KE, Ennett ST, Suchindran C, Benefield T, Linder GF. Assessing the effects of the dating violence prevention program safe dates using random coefficient regression modeling. Prev Sci. 2005;6(3):245–58. Hutchison CA, Waterman EA, Edwards KM, Hopfauf SL, Simon BR, Banyard VL. Attendance at a community-based, after school, youth-led sexual violence prevention initiative. J interpers Violence. 2022;37:23–4. Waterman EA, Edwards KM, Banyard VL, Chang H. Age and sexual orientation moderated the effects of a bystander-focused interpersonal violence prevention program for high school students. Prev Sci. 2022;23(1). Proctor E, Silmere H, Raghavan R, Hovmand P, Aarons G, Bunger A et al. Outcomes for implementation research: Conceptual distinctions, measurement challenges, and research agenda. Adm Policy Mental Health Mental Health Serv Res. 2011;38(2). Enders CK. Applied Missing Data Analysis. New York, NY, USA: Guildford; 2010. World Medical Association. Declaration of Helsinki. 2013. American Pyschological Association. Ethical Principles of Psychologists and Code of Conduct. Washington D.C.2017. Ordem dos Psicólogos. Código Deontológico da Ordem dos Psicólogos Portugueses 2024. Jewkes DE, Sikweyiya Y. Ethical and safety recommendations for research on perpetration of sexual violence. Pretoria, South Africa2012. Shields RT, Feder KA. The public health approach to preventing sexual violence. In: Jeglic EL, Calkins C, editors. Sexual violence: Evidence based policy and prevention. Cham: Springer International Publishing; 2016. pp. 129–44. Yüce M, Karabekiroğlu K, Yildirim Z, Şahin S, Sapmaz D, Babadaği Z et al. The psychiatric consequences of child and adolescent sexual abuse. Noro Psikiyatri Arsivi. 2015;52(4). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7924931","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Study protocol","associatedPublications":[],"authors":[{"id":542460953,"identity":"1791c82e-9162-4651-9da9-f9adfba6b6b3","order_by":0,"name":"Eunice Carmo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABFklEQVRIie3RPUvEMBjA8ScE6pLSNUXoNxAqhSAo+FVahLrIcVA4OknloC4Hrg76Hep2Y0ogLuHmygkX9xM63iLYaydf4jkK5k+WFH48SQpgs/3BQo45j3NKHKivNDjDxx3ESbRWR4GHhAg/EGIkJDp8KfPIn8qU/o4sC0ZjRZNKKpa3EwEH19MKu3MYnZrIM09pd5ekUoo93S4EMCXH2FWQGac0sRymNIot3bIjzUWI3RKSmZEkJd2uarVm2duWrNa7yBkOOxL5hUwx6qeQn4l/J5HuDhZ4IIQ/W5wTptJxfa9oRvj3xNu/aetNftn/ynYzOQ7Yo3jQr/OT0V5hGEM/7ft34qigsQF8JUOoADOx2Wy2/9Y7cTppPbP4qxsAAAAASUVORK5CYII=","orcid":"","institution":"University of Porto, University of Porto","correspondingAuthor":true,"prefix":"","firstName":"Eunice","middleName":"","lastName":"Carmo","suffix":""},{"id":542460954,"identity":"9bd509d3-6483-46af-a052-042bf34d9de6","order_by":1,"name":"Nélio Brazão","email":"","orcid":"","institution":"University of Coimbra, CINEICC – Center for Research in Neuropsychology and Cognitive Behavioral Intervention","correspondingAuthor":false,"prefix":"","firstName":"Nélio","middleName":"","lastName":"Brazão","suffix":""},{"id":542460957,"identity":"ec1844f7-c5aa-425b-b899-c485d4bc2ef4","order_by":2,"name":"Patrício Costa","email":"","orcid":"","institution":"University of Porto, University of Porto","correspondingAuthor":false,"prefix":"","firstName":"Patrício","middleName":"","lastName":"Costa","suffix":""},{"id":542460958,"identity":"9be1d3ca-fa59-4c9a-ab02-5288e9e50293","order_by":3,"name":"Bárbara Moreira","email":"","orcid":"","institution":"University of Porto, University of Porto","correspondingAuthor":false,"prefix":"","firstName":"Bárbara","middleName":"","lastName":"Moreira","suffix":""},{"id":542460959,"identity":"90173538-5a12-414b-baf8-891a7753b62a","order_by":4,"name":"Joana Carvalho","email":"","orcid":"","institution":"University of Aveiro","correspondingAuthor":false,"prefix":"","firstName":"Joana","middleName":"","lastName":"Carvalho","suffix":""}],"badges":[],"createdAt":"2025-10-22 15:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7924931/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7924931/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":95671360,"identity":"398e2a02-2bf8-4bbe-a451-3a526fca2527","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36111,"visible":true,"origin":"","legend":"","description":"","filename":"Figure1.docx","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/f6da41206f98e1668b9d10c8.docx"},{"id":95799230,"identity":"8ac4bbba-52fa-4b25-9714-37c3c8a79848","added_by":"auto","created_at":"2025-11-13 08:19:14","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":73349,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscriptunblinded.docx","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/c4a24288b93cfdbbd13d8d76.docx"},{"id":95671361,"identity":"f76ebf76-fec0-4426-9404-e42b69c9184b","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":16523,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/55c6fbff3421b6edc1222bbd.docx"},{"id":95799256,"identity":"15f45b5a-556b-41ea-be2a-f6af41e5feec","added_by":"auto","created_at":"2025-11-13 08:19:19","extension":"json","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7376,"visible":true,"origin":"","legend":"","description":"","filename":"19f35a83f7b54b4faf5c8fc04627a0e2.json","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/b4c7692aa8adc37c834b0fa0.json"},{"id":95671369,"identity":"5d919eb3-c218-4dc0-a1c7-b4cba7d9785e","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"xml","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":153543,"visible":true,"origin":"","legend":"","description":"","filename":"19f35a83f7b54b4faf5c8fc04627a0e21enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/076c1036360e7d8bed0efe7e.xml"},{"id":95798386,"identity":"b38b29d8-617f-4ff2-8d34-0855327c34eb","added_by":"auto","created_at":"2025-11-13 08:16:39","extension":"eps","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":64514,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage10.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/88bd74fb6e8b88185ee5cb3f.eps"},{"id":95671365,"identity":"b07e4762-1613-479c-bd4f-b49060d3c1ee","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":79589,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage11.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/41e7e9d9f4ab9cec8b09c191.eps"},{"id":95799779,"identity":"79dec9f1-0543-4156-8c08-4d0108e036b5","added_by":"auto","created_at":"2025-11-13 08:20:45","extension":"eps","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":553,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/1314297cd9f83a368c025437.eps"},{"id":95671366,"identity":"cb2bd375-7445-4685-aa68-9b83ca6f1c6a","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":553,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/855eed55e1a911c40f9abd1f.eps"},{"id":95798575,"identity":"f73e02fa-ba28-4b87-b8d7-93b9a7f2a5c1","added_by":"auto","created_at":"2025-11-13 08:17:09","extension":"eps","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":378,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage14.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/ca34d0a370090ce511443565.eps"},{"id":95671364,"identity":"5b22d991-e493-4ddf-947f-f3526caca453","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":553,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/fa8d6b2e1b46669da76be79a.eps"},{"id":95798413,"identity":"8df0ecaa-046f-4164-a874-7e899f9f6093","added_by":"auto","created_at":"2025-11-13 08:16:44","extension":"eps","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":65891,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage16.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/5af835f966e6a4cf824dbe8c.eps"},{"id":95798507,"identity":"3656e112-094d-4e22-baaf-64cce703ea37","added_by":"auto","created_at":"2025-11-13 08:16:56","extension":"eps","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":553,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/c16758a5cf9d77a331637acd.eps"},{"id":95671389,"identity":"159beba9-f1c2-43aa-b721-229583bea261","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":80999,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage3.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/e23818aba6a2a3a344b81af1.eps"},{"id":95671378,"identity":"d6a0da47-50c6-4ce5-89f2-6642f39ca5b4","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":553,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/0d44b3e2b7a91eac6da4f771.eps"},{"id":95671387,"identity":"8460d4ac-829f-41f3-8270-c6a2d224b0d4","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":101635,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage5.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/03e8a8d01c90b3ad039a2e38.eps"},{"id":95799820,"identity":"f23fa275-ce54-4e96-80cc-7e3663d6fdab","added_by":"auto","created_at":"2025-11-13 08:20:52","extension":"eps","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":99991,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage6.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/f53d988327eba88f6a5c66d4.eps"},{"id":95797353,"identity":"8d321c66-4208-4946-82a2-23b7bdedfef2","added_by":"auto","created_at":"2025-11-13 08:04:03","extension":"eps","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":554,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage7.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/43d2d5f6527b0cbf5d987da9.eps"},{"id":95671379,"identity":"20b78863-230d-4114-a35e-a19651c25cfc","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":554,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage7.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/b53866874df59b04c133b214.eps"},{"id":95671381,"identity":"e03c9117-2f65-4c37-9c26-f1b4eed0d579","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"eps","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":64635,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage9.eps","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/c07c36eb7e47df18f2459e8f.eps"},{"id":95671373,"identity":"cc8c156a-60d4-4954-8788-cdd974281788","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"jpeg","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17788,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/631028a459836a68cf0839e9.jpeg"},{"id":95671374,"identity":"6a7708ee-feae-4f80-b69c-950acfd8df35","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"jpeg","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":657343,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/d3711679fa6384992079975e.jpeg"},{"id":95798626,"identity":"e60123bf-5476-427a-b704-db6cf88e1737","added_by":"auto","created_at":"2025-11-13 08:17:21","extension":"jpeg","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":185777,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/2f8d613b59166253d45975b9.jpeg"},{"id":95671382,"identity":"c2a2bd21-c55a-427f-a291-e36e5b8fda16","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"jpeg","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1074,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/d53a1796c9165d52b7259db0.jpeg"},{"id":95797342,"identity":"f6dbe63f-0b9e-4447-ab85-6cd10a3efcde","added_by":"auto","created_at":"2025-11-13 08:03:46","extension":"jpeg","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17788,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/17f9e7a7684922571fafd57d.jpeg"},{"id":95798342,"identity":"cbca3aaa-6199-4a50-b064-4dc8d3a2676d","added_by":"auto","created_at":"2025-11-13 08:16:25","extension":"png","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5362,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/a7cb18dea16f8533a928d35b.png"},{"id":95671384,"identity":"37c4487a-6342-422f-b824-dac123bea5a4","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"png","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":104574,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/2ededf532793df93f56c9eb6.png"},{"id":95671380,"identity":"f57cb3f5-2bdc-4ea8-838e-21f8f23c1072","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"png","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":33961,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/56c67a811acc447e57349996.png"},{"id":95671383,"identity":"f0498249-fa3e-4419-a544-0ca52be890d2","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"png","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":935,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/ce16a3d495e0de143fa91b28.png"},{"id":95799213,"identity":"4fc4fbe3-a8fe-4856-8b57-2071200809cb","added_by":"auto","created_at":"2025-11-13 08:19:04","extension":"png","order_by":30,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5362,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/a9c10a4687a93b6cd19c390a.png"},{"id":95671392,"identity":"a0fca3ad-80aa-4215-b301-5bfa26e8e344","added_by":"auto","created_at":"2025-11-11 17:24:14","extension":"xml","order_by":31,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":148340,"visible":true,"origin":"","legend":"","description":"","filename":"19f35a83f7b54b4faf5c8fc04627a0e21structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/211ee99e2f1d090a41ed121f.xml"},{"id":95798817,"identity":"51777761-6f07-4b4b-a266-7c0d29b58929","added_by":"auto","created_at":"2025-11-13 08:17:54","extension":"html","order_by":32,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":167791,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/1883a9b964de7ea91eb4e67c.html"},{"id":95671359,"identity":"8a19fc78-6374-4952-8671-c17ce99fde3e","added_by":"auto","created_at":"2025-11-11 17:24:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":32547,"visible":true,"origin":"","legend":"\u003cp\u003eStudy Flow Diagram – SPIRIT Figure\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/730342c7f6e7ed0fee86cd28.png"},{"id":101751468,"identity":"7097e0c5-b60f-4098-997b-8a9696c3d3f7","added_by":"auto","created_at":"2026-02-03 10:20:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":732047,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7924931/v1/6d79f2c3-33c7-41c4-bc29-76b5a1fde9a6.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The prevention of sexual violence in school settings with adolescents: A study protocol for the cluster randomized trial of the SUN (Stand Up Now against sexual violence) Program","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSexual violence (SV) is a global public health issue that often affects adolescents (\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). A public health approach to SV prevention requires investment in primary prevention strategies that engage individuals from the general population to address SV before it occurs (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSchools bring together large and diverse groups of young people and are naturally equipped for fostering knowledge, prosocial attitudes, and skills, making them an effective setting for violence prevention (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Accordingly, many research groups have developed school-based primary prevention programs for SV, as recommended by international guidelines (\u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eNonetheless, researchers have highlighted relevant caveats that should not be overlooked. One urgent issue is the regional imbalance in the implementation of evidence-based programs, as 73% of those have been conducted in the U.S.A. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Moreover, most adolescent prevention programs have addressed SV in the context of dating violence, which may be ineffective, given that previous reviews found non-significant effects on SV outcomes in such programs (\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn line with these results, there has been a gradual shift in focus, with more recent programs approaching SV specifically (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). This is mainly due to an investment in bystander programs, which aim to enable individuals to mitigate the risk of SV by accurately identifying such situations and engaging in preventive actions. These may include confronting a person who is exploiting someone unable to provide consent, offering support to a victim, or reporting a violent incident (\u003cspan additionalcitationids=\"CR24 CR25 CR26\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). In short, the bystander approach centers primary prevention of SV on the public health argument, involving every member of every community in its prevention (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA recent review of bystander SV prevention programs for youth and adults in schools and other contexts found that most increased bystander behaviors and decreased the acceptance of myths, as well as sexually coercive behaviors (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Besides, these programs also tend to address SV risk and protective factors, by including content on potential mediators (e.g., empathy) and considering potential moderators (e.g., prior victimization) (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). In line with this, the present study draws on a bystander approach and prior evidence that empathy is a protective factor, while SV myths and sexism are risk factors for SV (\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eCurrent Study\u003c/h3\u003e\n\u003cp\u003eThis protocol describes the research project which aims to assess the efficacy of a new SV prevention program for adolescents: the SUN (Stand Up Now against sexual violence) Program, applied in Portugal. This will be an efficacy trial, as it will constitute the first evaluation of the program using a CRT design under conditions approximating an ideal implementation: a standardized manualized intervention, no concurrent programs, specialized external facilitators (i.e., not delivered by school staff), and objective outcomes. Nonetheless, some pragmatic elements will be present (such as broad inclusion criteria, the use of \"treatment as usual\" in control groups, and the absence of double blinding) reflecting the real-world constraints of implementing a universal primary prevention program in school settings (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e"},{"header":"Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003cdiv id=\"Sec4\" class=\"Section3\"\u003e\u003ch2\u003eStudy Design, Aims, and Hypotheses\u003c/h2\u003e\u003cp\u003eThis project will aim to develop, implement, and evaluate the efficacy of a new bystander primary prevention program for SV targeting high school adolescents in Portugal: the SUN (Stand Up Now against sexual violence) Program. The study will follow the CONSORT 2010 statement: extension to cluster randomized trials (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) and the Standards of Evidence for Efficacy, Effectiveness, and Scale-up Research in Prevention Science (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). Additionally, the trial has been registered as a cluster randomized trial (CRT) at ClinicalTrials.gov (Identifier: NCT06830278; Registered on 17 February 2025) (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThis will be a mixed-method, pragmatic, parallel-arm CRT (please see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e for the Study Flow Diagram) with the following aims: 1) to assess the program\u0026rsquo;s efficacy in increasing bystander attitudes, behaviors, and empathy, and reducing SV myths and sexism; 2) to examine whether changes are maintained at three, six, and nine months follow-up; 3) to explore mechanisms of change by testing whether reduced SV myths and sexism and increased empathy predict improvements in bystander outcomes; 4) to investigate whether age, gender, sexual orientation, or victimization history affect responsiveness; and 5) to assess the program\u0026rsquo;s acceptability and feasibility.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eBased on the theoretical framework, the following hypotheses will be developed: 1) Participants in the experimental group will show greater increases in bystander attitudes, behaviors, and empathy, and greater reductions in SV myths and sexism than the control group; 2) In the experimental group, reductions in SV myths and sexism and increases in empathy will predict improvements in bystander attitudes and behaviors; 3) Younger participants, those identifying with gender or sexual minority groups, and those with victimization histories will show greater responsiveness to the intervention.\u003c/p\u003e\u003cp\u003eThe randomized trial will have a longitudinal design with five time-points: baseline (one week before the first session of the SUN), post-test (one week after the last session of the SUN), three-month, six-month, and nine-month follow-up assessments. These time-points will balance the need to monitor long-term change with considerations of feasibility and participant acceptability. Ideally, a longer follow-up period (e.g., 12 to 18 months) would be included; however, evidence from studies with similar samples and outcomes that observed significant effects with comparable follow-up durations supports the adequacy of this approach (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). Procedures to minimize testing effects will include randomization, control groups, and statistical controls (i.e., statistical tests will be used to compare relevant psychological dimensions between groups; in case significant differences are found, these dimensions will be included as covariates in statistical analyses) (\u003cspan additionalcitationids=\"CR40\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e[Insert Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e about here]\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSetting and Sample\u003c/h3\u003e\n\u003cp\u003eEligible schools will include public, vocational, and private institutions in Northern and Central Portugal with at least two 10th or 11th grade classes and Portuguese-speaking students. Schools will also have to offer appropriate infrastructure and scheduling for assessments and sessions. Age will not be an exclusion criterion, given variability across regions and classes (typically 14\u0026ndash;19 years). The only individual exclusion criteria will be serious developmental, mental, or physical health conditions that prevented participation, as reported by caregivers or school staff.\u003c/p\u003e\u003cp\u003eAdolescents were selected based on epidemiological evidence indicating high SV prevalence in this group (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e); the differences in sexual victimization and perpetration in adolescence in comparison to childhood or adulthood (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e); and the risk of victimization and perpetration trajectories persisting into adulthood (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e). Grades 10 and 11 were chosen to increase adherence to follow-ups, minimizing dropout risk before high school completion in 12th grade.\u003c/p\u003e\n\u003ch3\u003eSample Size Estimation and Statistical Analysis Plan\u003c/h3\u003e\n\u003cp\u003eA priori sample size estimation accounted for the cluster randomized trial (CRT) design, in which classes are the unit of randomization. The trial includes two parallel arms (intervention vs. control) and five assessment points (baseline, post-test, 3-, 6-, and 9-month follow-ups).\u003c/p\u003e\n\u003ch3\u003eSample Size Estimation\u003c/h3\u003e\n\u003cp\u003eThe base sample size was calculated in G*Power 3.1 (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e) for a two-tailed t-test comparing two independent means, with α\u0026thinsp;=\u0026thinsp;.05, power\u0026thinsp;=\u0026thinsp;.80, and a standardized effect size of \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30, consistent with previous school-based bystander and prevention programs (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e). This analysis indicated that 352 participants (176 per group) are required under individual randomization.\u003c/p\u003e\u003cp\u003eBecause randomization occurs at the class level, the sample was inflated using the design effect (DE) formula:\u003c/p\u003e\u003cp\u003e\u003cem\u003eDE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1 + (\u003cem\u003em\u003c/em\u003e \u0026minus;\u0026thinsp;1) \u0026times; \u003cem\u003eICC\u003c/em\u003e\u003c/p\u003e\u003cp\u003eAssuming an average class size of \u003cem\u003em\u003c/em\u003e\u0026thinsp;=\u0026thinsp;15 students and an intraclass correlation coefficient (ICC)\u0026thinsp;=\u0026thinsp;0.03, typical for psychosocial outcomes in educational settings (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e), the design effect equals 1.42. Adjusting for clustering increases the total required sample to approximately 500 students (\u0026asymp;\u0026thinsp;250 per arm), corresponding to 34 classes (17 per arm).\u003c/p\u003e\u003cp\u003eTo accommodate 20% expected attrition over the 9-month follow-up (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e), the final recruitment target is approximately 600 students (\u0026asymp;\u0026thinsp;40 classes, 20 per arm). This sample size provides a minimum of 80% power to detect small-to-moderate effects and is sufficient for planned moderation and mediation analyses. If cluster sizes vary substantially, the design effect will be corrected using the coefficient of variation (CV) of class size (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFor the mechanism-of-change analyses, an a priori RMSEA-based power analysis (power4SEM; (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e)) indicated that N\u0026thinsp;\u0026asymp;\u0026thinsp;550 achieves 80% power for detecting model fit differences (testing RMSEA₀ = .05 vs. RMSEA₁ = .08, α\u0026thinsp;=\u0026thinsp;.05). The planned CRT sample (\u0026asymp;\u0026thinsp;600 participants) therefore ensures sufficient power for longitudinal structural equation modeling (SEM).\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eRecruitment and Randomization\u003c/h2\u003e\u003cp\u003eSchools that respond to the project invitation will participate in preliminary meetings where the research team will explain the program structure, consent and assent procedures, the randomization process, and assessment protocol. Schools will then be asked to evaluate their interest and feasibility conditions for participation, considering aspects such as the number of available classes, student numbers per class, gender distribution, and schedule compatibility. Once selected, each school will designate the specific classes to be included in the study. Subsequently, presentation sessions will be held with students and teachers from the selected classes to reiterate the information previously shared.\u003c/p\u003e\u003cp\u003eIn this project, the unit of randomization (i.e., the cluster) will be the class, so the study will include at least a control and experimental group per school. This decision was ethically and pragmatically driven, considering the balance of efforts and benefits between groups and feasibility conditions. Several procedures will be adopted to minimize contamination across conditions: school staff involved in the experimental groups will not work with control groups and vice versa; sessions for each group will be scheduled at different times and on different days to reduce interaction; control and experimental groups will use different classrooms; and only facilitators will have access to program materials.\u003c/p\u003e\u003cp\u003eClasses will be randomly assigned to either the intervention or control group using block randomization in a 1:1 ratio, performed after baseline assessments via a randomization software tool (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.randomizer.org/\u003c/span\u003e\u003cspan address=\"https://www.randomizer.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). Given the pragmatic nature of the trial, neither research staff, school staff, nor participants will be blinded to group allocation (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eIntervention and Control Group\u003c/h3\u003e\n\u003cp\u003eThe SUN is a manualized program that integrates psychoeducation with skill-building exercises and targets social norms, attitudes, emotions, and behaviors. The program will comprise ten weekly sessions of 50 to 60 minutes, delivered to mixed-gender groups, mirroring regular class settings to ensure ecological validity and in accordance with the current evidence in the field (\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e). The number of students per class (and session) is expected to vary between 10 and 25.\u003c/p\u003e\u003cp\u003eSessions will be facilitated by two psychologists and SV researchers with training in prevention programs for adolescents and in the implementation of the SUN. Supervision will be provided by the multidisciplinary research team, composed of an Assistant Professor with Habilitation in Forensic Psychology, Sexology, and Experimental Research; an Associate Professor in Research Methods and Statistics; an Assistant Professor in Forensic Psychology; and two PhD candidates specializing in Forensic Psychology.\u003c/p\u003e\u003cp\u003eThe SUN was designed in accordance with the good practice standards of prevention science (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e), namely the nine characteristics of effective prevention: comprehensive; theory driven; varied teaching methods; sufficient dosage; positive relationships; appropriately timed; socioculturally relevant; outcome evaluation; and well-trained staff (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e). Furthermore, the intervention was informed by best practices identified in prior research and adapted to the Portuguese context, following guidance for comprehensive, multi-session programs targeting mixed-gender groups (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e, \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eGrounded in bystander intervention theory, the SUN will train participants to: 1) understand the different manifestations of SV; 2) challenge social norms associated with tolerance of SV (i.e., SV myths and sexism); 3) recognize support resources for SV situations; 4) use proactive bystander behaviors to reduce SV risk; 5) use reactive bystander behaviors to mitigate SV consequences; and 6) demonstrate empathy for SV victims (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e). For a detailed description of the program sessions, please consult Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003e\u003cem\u003eThe SUN Program: Session Structure\u003c/em\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"614\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSession Theme\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eSession Goals\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 614px;\"\u003e\n \u003cp\u003eModule 1 \u0026ndash; Sexual Violence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eIntroduction; Sexual and reproductive rights\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eDefining SV\u003c/p\u003e\n \u003cp\u003eUnderstanding SV as a human rights violation\u003c/p\u003e\n \u003cp\u003eDescribing sexual and reproductive rights\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSV: behaviors and contexts\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eUnderstanding the variety of behaviors classified as SV\u003c/p\u003e\n \u003cp\u003eIdentifying the contexts in which SV occurs\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSexual consent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eDiscussing the concept of sexual consent\u003c/p\u003e\n \u003cp\u003eDistinguishing situations of sexual consent and non-consent\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSV myths\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eChallenging SV myths\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSexual teen dating violence\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eReflecting on sexual consent within dating relationships\u003c/p\u003e\n \u003cp\u003eChallenging SV myths in the context of dating violence\u003c/p\u003e\n \u003cp\u003eReflecting on online SV\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 614px;\"\u003e\n \u003cp\u003eModule II \u0026ndash;Bystander Intervention\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eThe role of a bystander\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eUnderstanding the concepts of bystander attitudes and behaviors\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eIdentifying proactive and reactive bystander behaviors\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eThe bystander effect\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eUnderstanding the bystander effect\u003c/p\u003e\n \u003cp\u003eIdentifying obstacles to bystander intervention\u003c/p\u003e\n \u003cp\u003eLearning to use helplines and support resources\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eBystander intervention\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eDistinguishing the 6 D\u0026rsquo;s of bystander intervention\u003c/p\u003e\n \u003cp\u003eApplying the 6D\u0026rsquo;s of bystander intervention to a case study\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eEmpathy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eUnderstanding the application of empathy to bystander intervention\u003c/p\u003e\n \u003cp\u003eDiscussing victims\u0026rsquo; testimonies\u003c/p\u003e\n \u003cp\u003eTraining empathic communication\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003eSession 10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 168px;\"\u003e\n \u003cp\u003eSummary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 316px;\"\u003e\n \u003cp\u003eApplying skills: communication about consent; empathic communication; bystander intervention\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\u003cp\u003e[Insert Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e about here]\u003c/p\u003e\u003cp\u003eThe control groups will follow their usual school schedule and will not receive any intervention beyond the standard curricular and extracurricular activities.\u003c/p\u003e\n\u003ch3\u003eMeasures\u003c/h3\u003e\n\u003cp\u003eAll outcomes will be assessed at the individual level, allowing for participant-level measurement of change while accounting for clustering in the analysis. Primary outcome measures will include: bystander attitudes measured by the Bystander Attitude Scale-Revised (BAS-R) (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e) and bystander behaviors measured by the Bystander Behavior Scale-Revised (BBS-R) (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e). Secondary outcomes measures will include: empathy measured by the Basic Empathy Scale-Adolescents (BES-A) (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e); sexual violence myths measured by sexual violence subscales of the Attitude Toward Dating Violence Scale (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e); sexism measured by the Sexism Detection Scale (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e). Social desirability measured by the Social Desirability scale (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e) will be included as a covariate.\u003c/p\u003e\u003cp\u003eThe primary outcome measures were selected considering the aim of the SUN: to develop bystander attitudes and behaviors. Secondary outcomes and mechanisms of change (i.e., empathy, SV myths and sexism) were selected according to theory and previous findings (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe assessment protocol will start with a sociodemographic survey including school year, age, gender identity, sexual orientation, and personal history of victimization. Glossaries will be included to ensure that participants understand every option available. The survey will end with a list of support resources that participants may wish to use in case of need, such as victim support services (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e).\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eBystander Attitude Scale-Revised\u003c/h2\u003e\u003cp\u003eThe Bystander Attitude Scale-Revised (modified version) is a self-report survey that measures bystander attitudes using 19 items (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e). This study uses a recent adaptation of this scale into Portuguese for adolescents, using only 13 items (Unpublished data). The Portuguese adaptation revealed three subscales: 1) high risk situations, about scenarios in which the victim faces an imminent threat of SV (6 items, e.g., \u0026ldquo;Confront a friend who plans to give someone alcohol to get sex.\u0026rdquo;) 2) proactive opportunities; regarding situations where there is an opportunity to learn about SV (2 items, e.g., \u0026ldquo;Take a class to learn more about sexual violence and abuse.\u0026rdquo;); and 3) post-assault interventions, corresponding to attitudes regarding supporting victims and reporting offenders (4 items, e.g., \u0026ldquo;Report a friend that committed a rape.\u0026rdquo;). In this survey, participants will be asked to rate how acceptable a behavior is for them (i.e., whether they were favorable to that behavior) on a Likert scale from 1 (not acceptable) to 5 (extremely acceptable). The three-factor structure of the Portuguese adaptation revealed good internal consistency (α\u0026thinsp;=\u0026thinsp;.86 for the total scale; α\u0026thinsp;=\u0026thinsp;.88 for high-risk situations, α\u0026thinsp;=\u0026thinsp;.60 for proactive behaviors and α\u0026thinsp;=\u0026thinsp;.83for post-assault behaviors) (Unpublished data).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eBystander Behavior Scale-Revised\u003c/h2\u003e\u003cp\u003eThe Bystander Behavior Scale-Revised (modified version) is a self-report survey similar to the BAS-R but which measures bystander behavior. Items are the same, but participants are asked to report whether they have had those behaviors (scale: \u0026ldquo;Yes\u0026rdquo;, \u0026ldquo;No\u0026rdquo;, \u0026ldquo;I wasn\u0026rsquo;t in that situation\u0026rdquo;) (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e). In this study, a Portuguese version of the BBS-R undergoing psychometric validation will be used (Unpublished Data).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eBasic Empathy Scale-Adolescents\u003c/h2\u003e\u003cp\u003eThe Basic Empathy Scale-Adolescents (BES-A) is a 16-item self-report questionnaire for adolescents that evaluates empathy in its affective and cognitive dimensions (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e). This study will use the Portuguese version, which has a two-factor structure: 1) cognitive empathy subscale (8 items, e.g., \u0026ldquo;I can often understand how people are feeling even before they tell me\u0026rdquo;); 2) affective empathy subscale (8 items, e.g., \u0026ldquo;After being with a friend who is sad about something, I usually feel sad\u0026rdquo;) (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e). Answers are given according to a five-point scale, ranging from 1\u0026thinsp;=\u0026thinsp;strongly disagree and 5\u0026thinsp;=\u0026thinsp;strongly agree. Authors reported that both subscales reached good internal consistency values (α\u0026thinsp;=\u0026thinsp;.80 for affective empathy and α\u0026thinsp;=\u0026thinsp;.85 for cognitive empathy). Both subscales were significantly and positively correlated with measures of social skills and significantly and negatively correlated with measures of aggression (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eAttitudes Toward Dating Violence Scale\u003c/h2\u003e\u003cp\u003eThe Portuguese adaptation of the Attitudes Toward Dating Violence Scale, a self-report questionnaire regarding dating violence for adolescents will be used to assess SV myths (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e). This study will use two subscales: the Sexual Violence perpetrated by Men subscale (12 items, e.g., \u0026ldquo;When boys are very sexually aroused, they cannot avoid having sex\u0026rdquo;) and the Sexual Violence perpetrated by Women subscale (12 items, e.g., \u0026ldquo;There is nothing wrong with a girl forcing her boyfriend to kiss her\u0026rdquo;) (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e). Answers are given according to a five-point Likert scale, ranging from 1\u0026thinsp;=\u0026thinsp;strongly disagree and 5\u0026thinsp;=\u0026thinsp;strongly agree. Authors reported that both subscales reached good internal consistency values (α\u0026thinsp;=\u0026thinsp;.80 for Sexual Violence perpetrated by Men and α\u0026thinsp;=\u0026thinsp;.83 for Sexual Violence perpetrated by Women).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eSexism Detection Scale\u003c/h2\u003e\u003cp\u003eThe Sexism Detection Scale (DSA) is a self-report questionnaire including 26 items aimed at detecting sexism in adolescents (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e, \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e). The scale includes two subscales: ten items measure benevolent sexism (e.g., Women are, naturally, more patient and tolerant than men.\u0026rdquo;) and 16 items measure hostile sexism (e.g., \u0026ldquo;The most adequate place for a woman is at home with her family\u0026rdquo;) (\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e). Answers are given according to a six-point scale, ranging from 1\u0026thinsp;=\u0026thinsp;strongly disagree and 6\u0026thinsp;=\u0026thinsp;strongly agree. The two-factor structure of the Portuguese adaptation revealed excellent internal consistency (α\u0026thinsp;=\u0026thinsp;.93; α\u0026thinsp;=\u0026thinsp;.93 for hostile sexism; and α\u0026thinsp;=\u0026thinsp;.85 for benevolent sexism).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eSocial Desirability Scale\u003c/h2\u003e\u003cp\u003eThe EDS-20 (Social Desirability Scale) is a 20-item self-report questionnaire developed to assess social desirability in diverse samples, including adolescents (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e). Items are answered on a dichotomous scale of \u0026ldquo;Yes\u0026rdquo; or \u0026ldquo;No\u0026rdquo;. An item example would be \u0026ldquo;Have you ever taken advantage of someone?\u0026rdquo;. This scale has shown appropriate psychometric properties in several Portuguese samples (\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eModerator variables (age, gender, sexual orientation, and personal history of victimization) will only be assessed at baseline, using the sociodemographic survey, and were selected according to the previous literature (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan additionalcitationids=\"CR71\" citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eResearch questions regarding the acceptability and feasibility (\u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e) of the SUN will be gathered via the team\u0026rsquo;s field notes, and participants\u0026rsquo; focus groups. Field notes will include the systematic registration of fidelity to the SUN Manual and perceptions regarding the acceptability and feasibility of procedures. The focus groups will be described in future publications.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis Plan\u003c/h2\u003e\u003cp\u003eAnalyses will follow the intention-to-treat principle. Given the hierarchical and longitudinal structure (time nested within participants, participants nested within classes), intervention effects will be examined using Linear Mixed-Effects Models (LMMs) with random intercepts for clusters and participants, and fixed effects for group, time, and their interaction (group \u0026times; time). This approach accounts for intra-cluster dependency and individual change trajectories while handling missing data under the Missing at Random (MAR) assumption via Full Information Maximum Likelihood (FIML) estimation (\u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e74\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eBaseline covariates will be controlled where appropriate. Moderation effects (age, gender, sexual orientation, victimization history) will be evaluated through interaction terms in the LMM framework.\u003c/p\u003e\u003cp\u003eTo explore mechanisms of change, longitudinal SEM (latent growth and cross-lagged models) will examine whether reductions in sexual violence myths and sexism, and increases in empathy, mediate improvements in bystander attitudes and behaviors over time.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eQualitative Analyses and Integration\u003c/h2\u003e\u003cp\u003eQualitative data will be analyzed to assess program acceptability, feasibility, and perceived impact. Integration of quantitative and qualitative results will occur at the interpretation stage, following a convergent mixed-methods design, to provide comprehensive insights into program efficacy, mechanisms of change, and contextual factors influencing implementation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003eEthical Considerations\u003c/h2\u003e\u003cp\u003eEthical approval for this project was granted by the Ethics Committee of the Faculty of Psychology and Education Sciences of the University of Porto (Approval number: Ref.\u0026ordf; 2022/07\u0026thinsp;\u0026minus;\u0026thinsp;03). The study follows ethical standards for research with human participants and psychological intervention in this context (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e, \u003cspan additionalcitationids=\"CR76 CR77\" citationid=\"CR75\" class=\"CitationRef\"\u003e75\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e78\u003c/span\u003e).\u003c/p\u003e\u003c/p\u003e\u003cp\u003e All assessments will be conducted by trained psychologists and researchers with experience in victim and offender support, ensuring that any disclosure of violence is managed according to the highest ethical standards. Participants will have access to facilitators or researchers outside the sessions through multiple contact channels. The team will be available to offer psychological support, referrals to specialized services, or assistance in reporting violent situations.\u003c/p\u003e\u003cp\u003eBefore enrollment, all participants will attend a presentation session outlining the sessions and study procedures, including consent, assent, and assessments. At the end of the session, participants under 18 will receive an assent form and a caregiver consent form; those 18 or older will receive a consent form for themselves. These procedures comply with the schools\u0026rsquo; legal requirements. Signed forms will be collected about a week later, allowing time for informed decisions.\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis research project aims to develop, deliver, and assess the efficacy of a new bystander primary prevention program for SV targeting high school adolescents in Portugal: the SUN (Stand Up Now against sexual violence) Program. This cluster randomized trial (CRT) has five main goals: 1) assess the program\u0026rsquo;s efficacy in improving bystander attitudes and behaviors, reducing SV myths and sexism, and increasing empathy; 2) evaluate the durability of these effects at three, six, and nine months follow-up; 3) explore mechanisms of change; 4) examine whether age, gender, sexual orientation, and victimization history moderate the program\u0026rsquo;s impact; and 5) to assess the program\u0026rsquo;s acceptability and feasibility.\u003c/p\u003e\u003cp\u003eThis project presents some limitations. Firstly, due to limited resources, the CRT expected sample size is smaller than in similar U.S.-based trials. However, sample size must be considered within the Portuguese research context. Secondly, recruitment will be limited to schools in the North and Centre of the country, which restricts national representativeness. Nonetheless, recruitment will cover at least two districts and includes various school types. Thirdly, survey data are subject to the usual limitations of self-report, although a social desirability scale will be included to mitigate bias, and focus groups will be used for triangulation.\u003c/p\u003e\u003cp\u003eThe SUN Program\u0026rsquo;s CRT is grounded in key premises: a) SV is a global public health concern (\u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e79\u003c/span\u003e); b) victimization and perpetration trajectories beginning in adolescence have severe consequences (\u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e80\u003c/span\u003e); c) school-based bystander programs are effective (\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). This study addresses significant gaps in adolescent SV prevention through a theory-based, methodologically rigorous approach. To our knowledge, the SUN is one of the first SV primary prevention programs evaluated through a CRT in Europe and the first in Portugal.\u003c/p\u003e\u003cp\u003eThis project is expected to have a meaningful impact on SV prevention among adolescents, raising awareness among students, caregivers, school staff, and the wider community. It aims to demonstrate relevant public health benefits and advance scientific knowledge in SV prevention through the dissemination of findings.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBAS-R\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBystander Attitude Scale-Revised\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBBS-R\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBystander Behaviour Scale-Revised\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBES-A\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBasic Empathy Scale-Adolescents\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCRT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster Randomized Trial\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCoefficient of Variation\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eDSA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSexism Detection Scale\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eEDS-20\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSocial Desirability Scale\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eFIML\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFull Information Maximum Likelihood estimation\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntraclass Correlation Coefficient\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLMMs\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eLinear Mixed-Effects Models\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMAR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMissing at Random\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRMSEA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eRoot Mean Square Error of Approximation\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSEM\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eStructural Equation Modeling\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSUN\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eStand Up Now against sexual violence Program\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSexual Violence\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eAuthors’ contributions:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEC: Conceptualization, Methodology, Software, Resources, Writing – original draft, Writing – review \u0026amp; editing, Visualization, Project administration, Funding acquisition\u003c/p\u003e\n\u003cp\u003eNB: Conceptualization, Methodology, Software, Writing – review \u0026amp; editing, Supervision, Funding acquisition\u003c/p\u003e\n\u003cp\u003ePC: Methodology, Software, Writing – review \u0026amp; editing, Supervision\u003c/p\u003e\n\u003cp\u003eBM: Conceptualization, Methodology, Writing – review \u0026amp; editing, Funding acquisition\u003c/p\u003e\n\u003cp\u003eJC: Conceptualization, Methodology, Writing – review \u0026amp; editing, Supervision, Project administration, Funding acquisition\u003c/p\u003e\n\u003cp\u003eEthics approval and consent to participate: Ethical approval for this study was obtained from the Ethical Committee of the Faculty of Psychology and Education Sciences of the University of Porto (Approval number: Ref.ª 2022/07-03). Written informed consent will be obtained from all participants and their legal guardians prior to participation. The study will be conducted in accordance with the Declaration of Helsinki and national data protection regulations.\u003c/p\u003e\n\u003cp\u003eConsent for publication: Not Applicable.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials: Not Applicable.\u003c/p\u003e\n\u003cp\u003eCompeting interests: The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eFunding statement: This study is supported by a PhD Grant from Fundação para a Ciência e Tecnologia (2022.11986.BD) awarded to Eunice Carmo. The study protocol has not undergone peer review as part of the funding process.\u003c/p\u003e\n\u003cp\u003eAcknowledgements: Not Applicable.\u003c/p\u003e\n\u003cp\u003eTrial Registration: This trial was prospectively registered with ClinicalTrials.gov (Identifier: NCT06830278; Registered on 17 February 2025).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAlexander KA, Miller E. Sexual violence: Another public health emergency. JAMA Netw Open. 2022;5(10).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBasile KC, DeGue S, Jones K, Freire, KD, Smith J, Raiford SG. JL. STOP SV: A technical package to prevent sexual violence. Atlanta, GA.; 2016.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKuo C, Mathews C, Abrahams N. Chapter 12 - Sexual violence as a global health problem: Current evidence and future directions. In: Orchowski LM, Gidycz CA, editors. Sexual assault risk reduction and resistance. San Diego: Academic; 2018. pp. 291\u0026ndash;308.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcMahon PM. The public health approach to the prevention of sexual violence. Sex Abuse. 2000;12(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNgo QM, Veliz PT, Kusunoki Y, Stein SF, Boyd CJ. Adolescent sexual violence: Prevalence, adolescent risks, and violence characteristics. Prev Med. 2018;116:68\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeGue S, Holt MK, Massetti GM, Matjasko JL, Tharp AT, Valle LA. Looking ahead toward community-level strategies to prevent sexual violence. J Women's Health. 2012;21(1):1\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFarrell AD, Meyer AL, Kung EM, Sullivan TN. Development and evaluation of school-based violence prevention programs. J Clin Child Adolesc Psychol. 2001;30(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFagan AA, Catalano RF. What works in youth violence prevention: A review of the literature. Res Social Work Pract. 2013;23(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCouncil of Europe. Convention on the protection of children against sexual exploitation and sexual abuse.; 2007.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCouncil of Europe. Convention on preventing and combating violence against women and domestic violence.; 2011.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. Ethical and safety recommendations for intervention research on violence against women. Building on lessons from the WHO publication Putting women first: ethical and safety recommendations for research on domestic violence against women. 2016.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. INSPIRE: Seven strategies for ending violence against children. 2016.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. Preventing intimate partner and sexual violence against women: Taking action and generating evidence. 2010.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. RESPECT women: Preventing violence against women. 2019.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. Understanding and addressing violence against women: Health consequences. 2012.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eUNPFA. The evaltuation of comprehensive sexuality education programmes: A focus on the gender and empowerment outcomes. 2015.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eUNESCO. Sexuality education review and assessment tool (SERAT). 2021.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLigiero D, Hart C, Fulu E, Thomas A, Radford L. What works to prevent sexual violence against children: Evidence review. Together for Girls; 2019.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEllsberg M, Arango DJ, Morton M, Gennari F, Kiplesund S, Contreras M et al. Prevention of violence against women and girls: what does the evidence say? Lancet. 2015;385(9977).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCarmo E, Braz\u0026atilde;o N, Carvalho J. The primary prevention of sexual violence against adolescents in school and community settings: A scoping review. J Sex Res. 2024.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePiolanti A, Foran HM. Efficacy of interventions to prevent physical and sexual dating violence among adolescents: A systematic review and meta-analysis. JAMA Pediatr. 2022;176(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePiolanti A, Jouriles EN, Foran HM. Assessment of psychosocial programs to prevent sexual violence during adolescence: A systematic review and meta-analysis. JAMA Netw Open. 2022;5(11).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBanyard V, Waterman E, Edwards K. Bystanders to prevent peer sexual violence: understanding patterns of prosocial behavior over time from early to later adolescence. J Youth Adolesc. 2021;50(10):1982\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKovalenko AG, Abraham C, Graham-Rowe E, Levine M, O\u0026rsquo;Dwyer S. What works in violence prevention among young people? A systematic review of reviews. Trauma Violence Abuse. 2022;23(5).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMiller E. Reclaiming gender and power in sexual violence prevention in adolescence. Violence Against Women. 2018;24(15).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKatz J, Moore J. Bystander education training for campus sexual assault prevention: An initial meta-analysis. Violence Vict. 2013;28(6):1054\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMujal GN, Taylor ME, Fry JL, Gochez-Kerr TH, Weaver NL. A systematic review of bystander interventions for the prevention of sexual violence. Trauma, Violence, \u0026amp; Abuse. 2021;22(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcMahon S, Postmus J, Koenick RA. Conceptualizing the engaging bystander approach to sexual violence prevention on college campuses. J Coll Student Dev. 2011;52.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBasile KC, Rostad WL, Leemis RW, Espelage DL, Davis JP. Protective factors for sexual violence: Understanding how trajectories relate to perpetration in high school. Prev Sci. 2018;19(8):1123\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFern\u0026aacute;ndez-Fuertes AA, Fern\u0026aacute;ndez-Rouco N, L\u0026aacute;zaro-Visa S, G\u0026oacute;mez-P\u0026eacute;rez E. Myths about sexual aggression, sexual assertiveness and sexual violence in adolescent romantic relationships. Int J Environ Res Public Health. 2020;17(23).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYbarra ML, Thompson RE. Predicting the emergence of sexual violence in adolescence. Prev Sci. 2018;19(4):403\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarchand E, Stice E, Rohde P, Becker CB. Moving from efficacy to effectiveness trials in prevention research. Behav Res Ther. 2011;49(1):32\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLoudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ. 2015;350(may08 1):h2147\u0026ndash;h.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCampbell MK, Piaggio G, Elbourne DR, Altman DG. Consort 2010 statement: extension to cluster randomised trials. BMJ. 2012;345.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGottfredson DC, Cook TD, Gardner FE, Gorman-Smith D, Howe GW, Sandler IN et al. Standards of evidence for efficacy, effectiveness, and scale-up research in prevention science: Next generation. Prevention Science. 2015;16(7).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eClinicalTrials.gov. The efficacy of the SUN program in adolescents (SUN)(NCT06830278) Clinical trial registration. U.S. National Library of Medicine.; 2025.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCulyba AJ, Fuhrman B, Barker G, Abebe KZ, Miller E. Primary versus secondary prevention effects of a gender-transformative sexual violence prevention program among male youth: A planned secondary analysis of a randomized clinical trial. J interpers Violence. 2023;38:19\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOrchowski LM, Malone S, Sokolovsky AW, Pearlman DN, Rizzo C, Zlotnick C, et al. Preventing sexual violence among high school students through norms correction and bystander intervention: A school-based cluster trial of Your Voice Your View. J Community Psychol. 2023;51(7):2861\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDimitrov DM, Rumrill PD. Jr. Pretest-posttest designs and measurement of change. Work. 2003;20(2):159\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFrench DP, Sutton S. Reactivity of measurement in health psychology: How much of a problem is it? What can be done about it? Br J Health Psychol. 2010;15(3):453\u0026ndash;68.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJones SMW, Shulman LJ, Richards JE, Ludman EJ. Mechanisms for the testing effect on patient-reported outcomes. Contemp Clin Trials Commun. 2020;18.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarcos V, Seijo D, Montes \u0026Aacute;, Arce R. Prevalence and quantification of the effects of sexual harassment victimization of school-aged adolescents. Children. 2024;11(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTorazzi E, Merelli V, Barbara G, Kustermann A, Marasciuolo L, Collini F et al. Similarity and differences in sexual violence against adolescents and adult women: The need to focus on adolescent victims. J Pediatr Adolesc Gynecol. 2021;34(3).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarbara G, Albertini V, Tagi VM, Maggioni L, Gorio MC, Cattaneo C, et al. Characteristics of sexual violence against adolescent girls: A 10 years' retrospective study of 731 sexually abused adolescents. Int J Women's Health. 2022;14:311\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYbarra ML, Petras H. Groups of sexual violence perpetration in a national sample of youth 13\u0026ndash;25 years of age. Prev Sci. 2021;22(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMumford EA, Liu W, Taylor BG. Longitudinal trajectories of perpetration of adolescent dating abuse in a national sample. Aggressive Behav. 2019;45(3).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFaul F, Erdfelder E, Lang A-G, Buchner A. G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39(2):175\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCoker AL, Bush HM, Brancato CJ, Clear ER, Recktenwald EA. Bystander Program Effectiveness to Reduce Violence Acceptance: RCT in High Schools. J Fam Violence. 2019;34(3):153\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeGue S, Niolon PH, Estefan LF, Tracy AJ, Le VD, Vivolo-Kantor AM, et al. Effects of Dating Matters\u0026reg; on Sexual Violence and Sexual Harassment Outcomes among Middle School Youth: a Cluster-Randomized Controlled Trial. Prev Sci. 2021;22(2):175\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMurray DM, Blistein JL. Methods to reduce the impact of intraclass correlation in group-randomized trials. Eval Rev. 2003;27(1):79\u0026ndash;103.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMatos MG, Gaspar T, Ferreira M, Sim\u0026otilde;es C. Health Behaviour in School-Aged Children: Portugal 2018 Report. Lisboa: FMH-ULisboa; 2021.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWolf EJ, Harrington KM, Clark SL, Miller MW. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety. Educ Psychol Meas. 2013;76(6):913\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eElias-Lambert N, Black B, Sharma Y. Middle school youth: satisfaction with and responses to a dating violence and sexual assault prevention program. J School Violence. 2010;9(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKettrey HH, Marx RA. Does the gendered approach of bystander programs matter in the prevention of sexual assault among adolescents and college students? A systematic review and meta-analysis. Arch Sex Behav. 2019;48(7).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNation M, Crusto C, Wandersman A, Kumpfer KL, Seybolt D, Morrissey-Kane E, et al. What works in prevention: Principles of effective prevention programs. Am Psychol. 2003;58:6\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeGue S, Valle LA, Holt MK, Massetti GM, Matjasko JL, Tharp AT. A systematic review of primary prevention strategies for sexual violence perpetration. Aggress Violent Beh. 2014;19(4):346\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoore GF, Audrey S, Barker M, Bond L, Bonell C, Hardeman W et al. Process evaluation of complex interventions: Medical Research Council guidance. BMJ. 2015.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eReidy DE, D\u0026rsquo;Inverno AS, Bogen KW, Swahn MH, Jacobs GM. Masculinity and violence against women from a social-ecological perspective: Implications for prevention. In: Geffner R, White JW, Hamberger LK, Rosenbaum A, Vaughan-Eden V, Vieth VI, editors. Handbook of interpersonal violence and abuse across the lifespan: A project of the National Partnership to End Interpersonal Violence Across the Lifespan (NPEIV). Cham: Springer International Publishing; 2022. pp. 2353\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcMahon S, Allen CT, Postmus JL, McMahon SM, Peterson NA, Lowe Hoffman M. Measuring bystander attitudes and behavior to prevent sexual violence. J Am Coll Health. 2014;62(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAnast\u0026aacute;cio S, Paula V, Luiza N-L, Daniel R, Jolliffe D. The Portuguese version of the Basic Empathy Scale (BES): Dimensionality and measurement invariance in a community adolescent sample. Eur J Dev Psychol. 2016;13(5):614\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSaavedra RMM, Machado C. Prevenir antes de remediar: Preven\u0026ccedil;\u0026atilde;o da viol\u0026ecirc;ncia nos relacionamentos \u0026iacute;ntimos juvenis. Escola de Psicologia: Universidade do Minho; 2010.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFernandes M, Moreira I, Silva A, S\u0026aacute; M, Ver\u0026iacute;ssimo C, Leit\u0026atilde;o M. Escala de Detecci\u0026oacute;n de Sexismo en Adolescentes: tradu\u0026ccedil;\u0026atilde;o e valida\u0026ccedil;\u0026atilde;o para o contexto portugu\u0026ecirc;s. Revista de Enfermagem Refer\u0026ecirc;ncia, V S\u0026eacute;rie; 2020.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAlmiro PA, Almeida D, Ferraz AM, Ferreira R, Silvestre MJ, Perdiz C, et al. Escala de Desejabilidade Social de 20 itens (EDS-20). In: Sim\u0026otilde;es MR, Almeida LS, Gon\u0026ccedil;alves MM, editors. Psicologia Forense: Instrumentos de Avalia\u0026ccedil;\u0026atilde;o. Lisboa: Pactor/Lidel; 2017.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSharkey JD, Reed LA, Felix ED. Dating and sexual violence research in the schools: Balancing protection of confidentiality with supporting the welfare of survivors. Am J Community Psychol. 2017;60:3\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJolliffe D, Farrington DP. Development and validation of the Basic Empathy Scale. J Adolesc. 2006;29(4).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePrice EL, Byers ES, Belliveau N, Bonner R, Caron B, Doiron D et al. The attitudes towards dating violence scales: Development and initial validation. J Family Violence. 1999;14(4).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRecio P, Cuadrado Guirado I, Ramos E. Propiedades psicom\u0026eacute;tricas de la Escala de Detecci\u0026oacute;n de Sexismo en Adolecentes (DSA). Psicothema. 2007;19(3):522\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNunes C, Paulino M, Sim\u0026otilde;es M. Avalia\u0026ccedil;\u0026atilde;o da Desejabilidade Social numa amostra de progrenitores em lit\u0026iacute;gio: Estudos de valida\u0026ccedil;\u0026atilde;o da EDS-20. Universidade de Coimbra2024.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarques A, Almiro P. Estudos de valida\u0026ccedil;\u0026atilde;o de duas escalas de avalia\u0026ccedil;\u0026atilde;o da desejabilidade social, EDS-20 e DESCA, numa amostra forense. Reposit\u0026oacute;rio da Universidade de Lisboa.; 2016.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFoshee VA, Bauman KE, Ennett ST, Suchindran C, Benefield T, Linder GF. Assessing the effects of the dating violence prevention program safe dates using random coefficient regression modeling. Prev Sci. 2005;6(3):245\u0026ndash;58.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHutchison CA, Waterman EA, Edwards KM, Hopfauf SL, Simon BR, Banyard VL. Attendance at a community-based, after school, youth-led sexual violence prevention initiative. J interpers Violence. 2022;37:23\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWaterman EA, Edwards KM, Banyard VL, Chang H. Age and sexual orientation moderated the effects of a bystander-focused interpersonal violence prevention program for high school students. Prev Sci. 2022;23(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eProctor E, Silmere H, Raghavan R, Hovmand P, Aarons G, Bunger A et al. Outcomes for implementation research: Conceptual distinctions, measurement challenges, and research agenda. Adm Policy Mental Health Mental Health Serv Res. 2011;38(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEnders CK. Applied Missing Data Analysis. New York, NY, USA: Guildford; 2010.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWorld Medical Association. Declaration of Helsinki. 2013.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAmerican Pyschological Association. Ethical Principles of Psychologists and Code of Conduct. Washington D.C.2017.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOrdem dos Psic\u0026oacute;logos. C\u0026oacute;digo Deontol\u0026oacute;gico da Ordem dos Psic\u0026oacute;logos Portugueses 2024.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJewkes DE, Sikweyiya Y. Ethical and safety recommendations for research on perpetration of sexual violence. Pretoria, South Africa2012.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShields RT, Feder KA. The public health approach to preventing sexual violence. In: Jeglic EL, Calkins C, editors. Sexual violence: Evidence based policy and prevention. Cham: Springer International Publishing; 2016. pp. 129\u0026ndash;44.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eY\u0026uuml;ce M, Karabekiroğlu K, Yildirim Z, Şahin S, Sapmaz D, Babadaği Z et al. The psychiatric consequences of child and adolescent sexual abuse. Noro Psikiyatri Arsivi. 2015;52(4).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Adolescents, Bystanders, High School, Primary Prevention, Protocol, Sexual Violence","lastPublishedDoi":"10.21203/rs.3.rs-7924931/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7924931/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSexual violence (SV) is a global public health issue that may arise during adolescence. This project aims to develop, deliver, and assess the efficacy of a new SV bystander prevention program for adolescents: the SUN (Stand Up Now against sexual violence) Program. This manualized bystander program, specifically targeting SV, will be implemented by psychologists in Portuguese schools. The SUN combines psychoeducation with skills training exercises, targeting social norms, attitudes, emotions, and behaviors. Program contents include sexual and reproductive rights, SV, sexual consent, bystander attitudes and behaviors, and empathy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis mixed-method study will involve a pragmatic parallel-arm cluster randomized controlled trial, conducted with the following goals: to assess the program’s efficacy regarding bystander attitudes and behaviors, SV myths, sexism, and empathy; to examine the maintenance of changes three, six, and nine months after the program’s completion; to assess mechanisms of change (i.e., to test whether the reduction of SV myths and sexism and the increase in empathy will predict increases in bystander attitudes and behaviors); to investigate whether age, gender, sexual orientation, and personal history of victimization will influence participants’ responsivity to the program; to assess acceptability and feasibility. The sample will include adolescents from high schools in the North and Centre of Portugal, enrolled in 10th and 11th grades. Participants will be assessed at five time-points using self-report questionnaires and focus groups will be conducted to gather their perceptions regarding the Program.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiscussion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis will be the first primary prevention program for SV to be assessed in a cluster randomized trial in Portugal, and one of the first to do so in Europe, particularly using a bystander approach.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial Registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trial was prospectively registered with ClinicalTrials.gov (Identifier NCT06830278 Registered on 17 February 2025).\u003c/p\u003e","manuscriptTitle":"The prevention of sexual violence in school settings with adolescents: A study protocol for the cluster randomized trial of the SUN (Stand Up Now against sexual violence) Program","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-11 17:24:08","doi":"10.21203/rs.3.rs-7924931/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b9fa856f-6e74-43ab-bbbe-ca0b74094902","owner":[],"postedDate":"November 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-30T01:09:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-11 17:24:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7924931","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7924931","identity":"rs-7924931","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}