How Should Sincerity Be Measured? A Rasch-Based Validation of the Adolescent Sincerity Scale

Although various instruments for measuring sincerity have been developed, limitations remain regarding comprehensive construct validity, sample diversity, and the application of Rasch analysis in psychometric evaluation among student populations in Indonesia. Sincerity is a multidimensional spiritual value that contributes to personal integrity, psychological well-being, and positive social relationships. This study aims to develop a sincerity instrument with adequate psychometric characteristics using the Rasch Analysis approach. The study employed an instrument development method involving 759 high school and vocational high school students in Yogyakarta, selected through stratified random sampling. The analysis results showed a person measure of 1.18 logits, indicating that the respondents’ average level of sincerity was above the item difficulty level. The instrument demonstrated excellent item quality with an item reliability of 0.99 and sufficient evidence of unidimensionality, as indicated by a raw variance explained by measures of 32.6%. Overall, this instrument is suitable for measuring students’ levels of sincerity and contributes to the development of values education as well as more effective guidance and counseling services.