DASS-21: assessment of psychological distress through the Bifactor Model and item analysis

Abstract

The term distress has been used to refer to a continuous variable operationalized through symptoms of depression, anxiety, and stress. In this study, psychological distress is measured using the Depression, Anxiety, and Stress Scale (DASS-21). Confirmatory Factor Analysis compared the fit of different measurement models for the DASS-21, with the parameters of the items verified through the Andrich rating scale model. A non-clinical sample of 530 participants (mean age=24.35±6.55 years; 71.89% women) responded to the instrument. According to the theoretical hypothesis, the results indicated a better fit for the bifactor model, composed of three specific factors (depression, anxiety, and stress) and a general factor (general psychological distress). The assessment of the item properties allowed for a better understanding of the organization of the continuum represented by the construct psychological distress. It is possible to conclude that the Brazilian version of the DASS-21 is an adequate measure for psychological distress.

Factor structure and psychometric properties of the Jordanian version of the depression anxiety stress scale (DASS‐21)

“…The results showed a significantly better fit for the bifactor model with one general factor and three specific factors (depression, anxiety, and stress), a finding that is consistent with the results of several recent studies. 1 , 7 , 10 , 23 , 32 , 34 , 55 , 56 , 57 , 58 This finding may resolve the controversy and disparity with respect to the factor structure of the DASS‐21 scale, as most studies conducted in the Arab world, despite their scarcity, produced mixed results; some of them identified one common factor for general distress 40 or two factors, 37 whereas others supported the original structure with three correlated factors 39 and still others highlighted the need for versions of DASS‐21 with 20 items, 36 18 items, 17 items, 40 or 16 items. 37 The current study, which is the first in Jordan, aligns with the latest results of previous international studies, as it confirms the importance of the bifactor structure without deleting any item from the original scale.…”

“…Due to the general factors, there is very little reliable variance. 53 , 55 In other words, using the total score on the DASS‐21 to measure general distress is preferable to using the scores on the three subscales. The correlations of the three subscales with measures of similar–different constructs were generally adequate, consistent with previous studies.…”

“…Given these small values of the ω H coefficients, the presence of the general factor score and the subscale scores interprets the subscales' ability to accurately indicate the unique constructs as very limited. Due to the general factors, there is very little reliable variance 53,55 . In other words, using the total score on the DASS‐21 to measure general distress is preferable to using the scores on the three subscales.…”