Psychometric properties of the Korean version of the effort–reward imbalance questionnaire: a study in a petrochemical company

Abstract

To evaluate the criterion validity, factorial validity, and internal consistency of Korean version of effort-reward imbalance (ERI) for the scales of effort, reward, and overcommitment as well as to examine the effect of psychosocial factors on physical and mental illness among petroleum refinery workers in South Korea. The Korean version of ERI questionnaire was constructed using the translation and back-translation technique, and its psychometric properties were explored among 908 male workers in a large petroleum refinery in South Korea in 2002. Cronbach's alpha coefficient was used to test internal consistency. An exploratory factor analysis was conducted on all items of the instrument. Confirmatory factor analyses were conducted on each dimension of effort, reward and overcommitment. Physical and mental health was measured by self-rated health (SF-8). The lowest tertiles of the scores were defined as illness. Multiple logistic regression models were used to test the effect of job stress on the physical and mental health (criterion validity of ERI scales). The Cronbach's alpha coefficients for effort, reward, and overcommitment were 0.71, 0.86, and 0.75, respectively, indicating satisfactory internal consistency. Exploratory factor analysis found three latent factors, which closely corresponded to the theoretical structure of the ERI model. Acceptable construct validity was shown using confirmatory factor analysis. The highest tertile of effort-reward ratio was significantly associated with physical illness (OR 2.4, 95% CI 1.7-3.6) and mental illness (OR 2.9, 95% CI 2.0-4.2), compared to lower tertiles. Overcommitment was significantly associated with mental illness, but not with physical illness. These findings contribute to the validity and reliability of the Korean ERI questionnaire. Importantly, in the context of a rapid change in the labour market, the lack of reciprocity between efforts and rewards at work is strongly associated with self-rated physical and mental health.