Factor structure and measurement invariance of the Penn Inventory of Scrupulosity-Revised (PIOS-R) across Christian, Jewish, and Muslim groups

Abstract

The revised Penn Inventory of Scrupulosity (PIOS-R) is widely used. Support for its factor structure is mixed across either a two-factor or a bifactor model. Normed on a primarily Christian sample, researchers use the PIOS-R to examine scrupulosity across religious groups. This study's primary aims were to clarify the PIOS-R's factor structure in a religiously diverse sample and determine whether the PIOS-R shows measurement invariance across religious groups. A secondary aim was to evaluate psychometric properties. U.S. participants (N = 718) who self-reported as Christian, Jewish, or Muslim were recruited using MTurk. Multiple group CFA indicated that a two-factor solution comprised of Fear of God (FOG) and Fear of Sin (FOS) provided the best-fitting model. Configural, metric, and scalar invariance held across religious groups. Internal consistency was strong for the full scale (ω_t = .96) and both FOS (ω_t = .95) and FOG (ω_t = .92) subscales. The PIOS-R was more strongly correlated with DOCS Scrupulosity (r = .71) than with DASS-21 Depression (r = .58), DASS-21 Anxiety (r = .66), or a measure of religiosity (SCSRFQ; r = .36), supporting relative discriminant validity. The PIOS-R appears appropriate for assessing scrupulosity within and among these religious groups.