Psychiatric Quarterly, 2025 (SSCI)
The purpose of this mixed methods research, conducted as three separate studies, is to explore university students' experiences with peer jealousy, develop the Peer Jealousy Scale (PJS) considering these experiences, and test the developed measurement tool in a hypothetical model. In Study I (N = 14), qualitative research yielded three overarching themes: "the behavioural aspect of peer jealousy", "the emotional aspect of peer jealousy", and "the cognitive aspect of peer jealousy". Based on these three themes, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), item analysis, Item Response Theory (IRT), test–retest analysis, criterion correlation validity, and reliability analyses were conducted for the PJS in Study II (N = 971). CFA validated the 14-item PJS developed by EFA. In the IRT, all items demonstrated excellent discrimination. As a result of the PJS's significant correlation with the Benign-Malicious Envy Scale (BeMaS), the validity of the criterion correlation was established, and the reliability of the scale was demonstrated using a variety of reliability coefficients. In Study III (N = 515), it was determined that peer jealousy and loneliness play serial multiple mediating roles in the relationship between self-esteem and harmony in life. All findings in this mixed methods study have expanded our understanding of peer jealousy.