Marcin Wojtasiński

The main goal of the research was to increase knowledge on the psychometric properties of the Prayer Importance Scale (PIS). The study analyzed the structure of test items using item response theory (IRT), Mokken scale analysis (MSA), and confirmatory factor analysis (CFA) to establish factorial structure of the method. Measurement invariance (MI) was calculated in groups differentiated by three criteria: religiosity, gender, and age. MI verifies whether test items measure the construct in the same way across different groups. The Structure and Level of Religiosity Test (SLRT) was used to examine the level of religiosity in participants. In a study conducted with a sample of n = 566 adults (Mage = 49.16 years; SDage = 15.72), two religious groups were identified based on a median distribution: with low (n = 275) and high (n = 291) levels of religiosity. Two groups differentiated by gender, men (n = 284) and women (n = 282), were equivalent per age period: early (age 25–39; n = 192), middle (age 40–59; n = 187), and late adulthood (age 60+; n = 187). Results of the analyses show high homogeneity of items comprising PIS, as well as strict invariance for the three distinguished criteria. Results of the study provide extended knowledge about psychometric properties of PIS and the ability to compare results due to religiosity, gender, and age.