Comparing Paid and Diamond Open Access: Metrics from Engineering Journals

This study investigates and compares Open Access journals charging Article Processing Charges (APC) and Diamond Open Access journals in Engineering, indexed in Scopus. It analyzes metrics like CiteScore, citations, published articles, and the percentage of cited articles from 2020 to 2023, categorized by quartiles (Q1–Q4) and the top 10%. The dataset includes 757 journals: 504 APC-charging and 253 Diamond, representing only 8.4% of active journals in this field. Findings indicate that APC journals have higher averages in CiteScore and citations, particularly in Q1 and top 10%, although they show more significant variability. Diamond journals display consistency in relative metrics and surpass APC journals in the percentage of cited articles within the top 10%. Additionally, APC fees are highest in top-tier quartiles, posing accessibility challenges for less-funded researchers. Despite these differences, both models play complementary roles, balancing impact and accessibility. The results highlight the need for inclusive policies to strengthen Diamond Open Access while acknowledging the visibility advantages of APC models. These findings provide a foundation for future research and editorial strategies in scientific publishing, particularly in Engineering, while suggesting paths to achieve equity and sustainability in Open Access dissemination.