Psychometric examination of modified version of Kansas Marital Satisfaction Scale (KMSS)

Background: Romantic relationships significantly influence physical and mental health. Existing measures of marital or relationship satisfaction often face limitations such as low internal consistency, excessive length, focus on counseling settings, or applicability only to married individuals. With evolving partnership dynamics, a concise and reliable tool applicable across various relationship types is needed. This study aimed to revise the Kansas Marital Satisfaction Scale (KMSS) to assess general relationship satisfaction and evaluate its psychometric properties. Methods: The original KMSS was modified to encompass satisfaction in all types of romantic partnerships. Two samples were utilized: the first (n = 280) to explore basic psychometric characteristics and validity, and the second (n = 946) for a detailed examination of the scale's functioning. Confirmatory factor analysis (CFA) assessed the factor structure, while item response theory (IRT) analyses evaluated item characteristics. Measurement invariance across gender and marital status was tested. Hypotheses regarding associations with neuroticism, well-being, education, gender, and age were examined. Results: The revised KMSS demonstrated excellent psychometric properties, with high reliability (Cronbach's α > 0.90) and a unidimensional factor structure confirmed by CFA. Measurement invariance was established across genders and between married and unmarried participants. IRT analysis indicated high discrimination parameters for all items. The KMSS score was negatively associated with trait neuroticism (r = –0.11, p < 0.001) and positively associated with well-being (r = 0.28, p < 0.001). No significant associations were found between KMSS scores and length of relationship, education level, gender, or age after controlling for covariates. Conclusion: The revised KMSS is a reliable and valid instrument for assessing relationship satisfaction across diverse types of partnerships. Its brevity and robust psychometric properties make it suitable for future research exploring the links between relationship satisfaction and health outcomes.