extended · article · 2009

Rasch model analysis of the Depression, Anxiety and Stress Scales (DASS)

Tracey Shea; Alan Tennant; Julie Pallant; David Andrich

BACKGROUND: There is a growing awareness of the need for easily administered, psychometrically sound screening tools to identify individuals with elevated levels of psychological distress. Although support has been found for the psychometric properties of the Depression, Anxiety and Stress Scales (DASS) using classical test theory approaches it has not been subjected to Rasch analysis. The aim of this study was to use Rasch analysis to assess the psychometric properties of the DASS-21 scales, using two different administration modes. METHODS: The DASS-21 was administered to 420 participants with half the sample responding to a web-based version and the other half completing a traditional pencil-and-paper version. Conformity of DASS-21 scales to a Rasch partial credit model was assessed using the RUMM2020 software. RESULTS: To achieve adequate model fit it was necessary to remove one item...