Psychometric properties of the Positive Mental Health Scale (PMH-scale)

BACKGROUND: In recent years, it has been increasingly recognized that the absence of mental disorder is not the same as the presence of positive mental health (PMH). With the PMH-scale we propose a short, unidimensional scale for the assessment of positive mental health. The scale consists of 9 Likert-type items. METHODS: The psychometric properties of the PMH-scale were tested in a series of six studies using samples from student (n = 5406), patient (n = 1547) and general (n = 3204) populations. Factorial structure and measurement equivalence were tested with the measurement invariance testing. The factor models were analysed with the maximum likelihood procedure. Internal consistency was examined using Cronbach's alpha, test-retest reliability, convergent and divergent validity was examined by Pearson correlation. Sensitivity to (therapeutic) change was examined with the t-test. RESULTS: Results confirmed unidimensionality, scalar invariance across samples and over time, high internal consistency, good retest-reliability, good convergent and discriminant validity as well as sensitivity to therapeutic change. CONCLUSIONS: These findings suggest that the PMH-Scale indeed measures a single concept and allows us to compare scores over groups and over time. The PMH-scale thus is a brief and easy to interpret instrument for measuring PMH across a large variety of relevant groups.