Measuring stress in clinical and nonclinical subjects using a German adaptation of the Perceived Stress Scale

<i>Background/Objective</i>: Stress is perceived differently across individuals, which might be particularly true for nonclinical and clinical subjects. For this reason, we tested a German adaption of the 10-item Perceived Stress Scale (PSS-10) for model fit and measurement invariance in a big nonclinical and clinical sample. <i>Method</i>: We (1) conducted multiple confirmatory factor analysis (CFA) in 1,248 nonclinical subjects and 575 outpatients, (2) measurement invariance with multigroup CFA, (3) assessed correlations with relevant constructs and (4) calculated internal consistencies for overall stress and the subscales Helplessness and Self-efficacy. <i>Results</i>: In both samples, CFA revealed a robust two-factorial structure with an excellent model fit. Group comparisons revealed strict measurement invariance. Correlations with associated measures support validity. Internal consistencies were good to very good. <i>Conclusions</i>: We show highly satisfactory psychometric properties of the German PSS-10 for nonclinical and clinical individuals. Measurement invariance analyses demonstrated that varying stress levels of people with a different mental health status are due to true interindividual differences.