Validation of the Japanese Version of the Subjective Underemployment Scale

Underemployment is a multidimensional construct capturing different forms of inferior or low-quality employment, but no comprehensive underemployment scales exist in Japanese. Therefore, this study validated a Japanese version of the Subjective Underemployment Scale (J-SUS) among nonregular employees across two studies. In Study 1, we conducted exploratory and confirmatory factor analysis, finding the same six-factor structure as the original scale (underpay, status, hours, temporary work, field, and poverty wage employment). The J-SUS dimensions were also positively correlated with perceived overqualification, financial deprivation, and relative deprivation, and were negatively correlated with pay satisfaction and person–job fit. Study 2 tested predictive validity using a random intercept cross-lagged panel model across three waves. At the within-person level, poverty wage employment positively predicted turnover intention and job performance and negatively predicted job satisfaction. In addition, field underemployment positively predicted job satisfaction, turnover intention positively predicted hours discrepancy, and career commitment negatively predicted hours discrepancy.