Factorial invariance and stability of the effort-reward imbalance scales: A longitudinal analysis of two samples with different time lags

Background; Key measures of Siegrist's (1996) Effort-Reward Imbalance (ERI) Model (i.e., efforts, rewards, and overcommitment) were psychometrically tested. Purpose: To study change in organizational interventions, knowledge about the type of change underlying the instruments used is needed. Next to assessing baseline factorial validity and reliability, the factorial stability over time-known as alphabeta-gamma change-of the ERI scales was examined. Methods: Psychometrics were tested among 383 and 267 healthcare workers from two Dutch panel surveys with different time lags. Results: Baseline results favored a five-factor model (i.e., efforts, esteem rewards, financial/career-related aspects, job security, and overcommitment) over and above a three-factor solution (i.e., efforts, composite rewards, and overcommitment). Considering changes as a whole, particularly the factor loadings of the three ERI scales were not equal over time. Findings suggest in general that moderate changes in the ERI factor structure did not affect the interpretation of mean changes over time. Conclusion: Occupational health researchers utilizing the ERI scales can feel confident that self-reported changes are more likely to be due to factors other than structural change of the ERI scales over time, which has important implications for evaluating job stress and health interventions.