Psychometric evaluation of the Questionnaire of Life Satisfaction (FLZ^M) in a representative population sample

Life satisfaction is a key construct within the salutogenetic framework of health and requires reliable assessment tools for research and clinical practice. This study evaluates the psychometric properties of the widely used Questionnaire of Life Satisfaction (FLZ^M for General Life Satisfaction).

A total of N = 2,503 (53.10 % female) participants from a representative German population sample completed the questionnaire alongside measures of sociodemographic variables, depressive and anxiety symptoms, suicidal ideation, and mood. Item and scale characteristics, as well as internal consistency, were examined. The hypothesized two-factor structure (satisfaction and importance) was tested using a confirmatory factor analysis. Measurement invariance was assessed across gender, age groups, and the presence of depressive and anxiety symptoms. Group differences and criterion validity were analyzed.

The revised two-factor model, including correlated residuals for identical life domains, demonstrated improved fit compared to the proposed model. Internal consistency was good for both subscales (McDonald's ω = .87 for the total scale). Measurement invariance was supported across all examined groups. As expected, life satisfaction was negatively correlated with depressive and anxiety symptoms, suicidal ideation, and negative mood states, and positively correlated with vigor.

The FLZ^M for General Life Satisfaction showed solid psychometric properties and measurement invariance in a representative German sample. These findings support its validity as a reliable instrument for assessing life satisfaction, which can contribute to the improved implementation and development of targeted interventions at an individual level.