Psychometric validation and measurement invariance of the Polish Multi-Affect Indicator across diverse demographic and occupational groups

The present study investigated the psychometric properties and validity of the Polish adaptation of the Multi-Affect Indicator (MAI), a scale designed to measure core affect at work. Specifically, we examined: (a) factor structure; (b) measurement invariance across sex, age, occupational group, and administration mode; (c) intergroup differences in work-related affective well-being; (d) internal, convergent, and discriminant validity; and (e) temporal stability. We conducted three studies with employee samples from diverse occupational sectors (N1 = 1,582; N2 = 326; N3 = 76). Results supported a correlated four-factor model consistent with the original MAI structure. In Study 1, the scale demonstrated scalar invariance across sex, age, and occupational groups, with strict invariance supported for sex and occupational group. In Study 2, the factor structure was replicated, and invariance analyses supported comparability across sex and occupational groups, although occupational-group results should be interpreted cautiously because some absolute-fit indices were elevated. The scale also achieved scalar invariance between the online Study 1 sample and the paper-and-pencil Study 2 sample. The Polish MAI demonstrated strong internal consistency, evidence of convergent and discriminant validity, and moderate one-week temporal stability. Overall, the results support the Polish MAI as a reliable and valid tool for assessing multidimensional affective well-being in occupational settings.