Psychometric properties of the Satisfaction with Job Life Scale in Portuguese workers: A systematic study based on the IRT and CFA modeling

Job satisfaction is related to better physical and mental health, as well as to factors specifically related to work. In this context, the measurement of work satisfaction is important for organizations that profess an interest in engaged and satisfied workers. Therefore, this study aims to examine the psychometric properties of the Satisfaction with Job Life Scale (SWJLS) in Portuguese workers by combining the procedures of the Classical Test Theory (CTT) and the Item Response Theory (IRT). Specifically, internal structure of the scale was studied, its reliability (consistency), correlations with other measures of wellbeing (life satisfaction, loneliness, emotional wellbeing at work, and job satisfaction) were also estimated, and finally, the sacle waqs tested for gender measurement invariance. Participants were 404 workers, 61% women and 39% men, aged between 18 and 64 years (M = 36.85; SD = 14.50). Confirmatory Factor Analysis indicated that the one-dimensional model of the SWJLS was adequate (Robust χ2(5) = 9.89, p = .078; CFI = .993; RMSEA = .049, 90% CI [.000 - .094]; SRMR = .011.) and had good internal consistency (ω = .947, 95% CI [.936, 956]; α = .947, 95% CI [.935, .955]). Subsequent analyses revealed that the scores of the SWJLS were related to other measures of job satisfaction (r = .742), job-related emotional well-being (r = .628), satisfaction with life (r = .808) and loneliness (r = -.455). Factorial invariance suggests that the structure of the SWJLS measures the same construct (satisfaction with work-life) in both female and male workers. Moreover, IRT analysis suggests that higher levels of work-life satisfaction are needed to choose the upper response options, while a very low level of work-life satisfaction is required to increase the likelihood of choosing the lower response options. In this sense, the SWJLS is useful and reliable, especially for identifying people with low levels of job satisfaction. These findings support the validity of the SWJLS and indicate that the Portuguese version is a brief instrument with good psychometric characteristics for measuring work-life satisfaction.
Classical test theory; Job satisfaction; Item response theory; Measurement; Portuguese workers.