Validating the short measure of the Effort‐Reward Imbalance Questionnaire in older workers in the context of New Zealand

Objectives The objective of this study was to validate a short version of the Effort‐Reward‐Imbalance (ERI) questionnaire in the context of New Zealand among older full‐time and part‐time employees. Methods Data were collected from 1694 adults aged 48‐83 years (mean 60 years, 53% female) who reported being in full‐ or part‐time paid employment in the 2010 wave of the New Zealand Health, Work and Retirement study. Scale reliability was evaluated by item‐total correlations and Cronbach's alpha. Factorial validity was assessed using multi‐group confirmatory factor analyses assessing nested models of configural, metric, scalar and strict invariance across full‐ and part‐time employment groups. Logistic regressions estimated associations of effort‐reward ratio and over‐commitment with poor physical/mental health, and depressive symptoms. Results Internal consistency of ERI scales was high across employment groups: effort 0.78‐0.76; reward 0.81‐0.77, and over‐commitment 0.83‐0.80. The three‐factor model displayed acceptable fit in the overall sample ( X 2 / df = 10.31; CFI = 0.95; TLI = 0.94; RMSEA = 0.075), and decrements in model fit indices provided evidence for strict invariance of the three‐factor ERI model across full‐time and part‐time employment groups. High effort‐reward ratio scores were consistently associated with poor mental health and depressive symptoms for both employment groups. High over‐commitment was associated with poor mental health and depressive symptoms in both groups and also with poor physical health in the full‐time employment group. Conclusions The short ERI questionnaire appears to be a valid instrument to assess adverse psychosocial work characteristics in old full‐time and part‐time employees in New Zealand. (J Occup Health 2017; 59: 495‐505) doi: 10.1539/joh.17‐0044‐OA