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.摘要：“痛苦”这一术语常被用于指代通过抑郁、焦虑与压力症状进行操作化定义的连续变量。本研究采用抑郁焦虑压力量表（Depression, Anxiety, and Stress Scale, DASS-21）对心理痛苦（psychological distress）进行测量。研究通过验证性因子分析（Confirmatory Factor Analysis）比较了DASS-21不同测量模型的拟合效果，并借助安德里希等级量表模型（Andrich rating scale model）验证了条目参数。本次研究共纳入530名非临床被试，其平均年龄为24.35±6.55岁，女性占比71.89%，所有被试均完成了该量表的作答。根据预设的理论假设，研究结果显示双因子模型（bifactor model）具备更优的拟合效果，该模型包含三个特定因子（抑郁、焦虑与压力）以及一个一般因子（一般心理痛苦）。对条目属性的评估能够帮助研究者更好地理解心理痛苦这一心理构念所代表的连续统的组织架构。综上可得出结论：DASS-21的巴西版本是适用于心理痛苦评估的有效测量工具。