Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Dec 26, 2022
Open Peer Review Period: Dec 25, 2022 - Feb 19, 2023
Date Accepted: Apr 17, 2023
(closed for review but you can still tweet)
The Depression Anxiety Stress Scale 21: Graded Response Model Analysis and Computer Adaptive Test Simulation
ABSTRACT
Background:
The Depression Anxiety Stress Scale 21 (DASS-21) is a mental health screening tool with conflicting research on its factor structure. No studies have yet attempted to develop a Computerised Adaptive Test (CAT) version of it.
Objective:
This study calibrated items for, and simulated, a DASS-21 CAT using a non-clinical sample.
Methods:
An evaluation sample (n = 580) was used to evaluate the DASS-21 scales via confirmatory factor analysis, Mokken, and Graded Response Modeling. A CAT was simulated with a validation sample (n = 248) and a simulated sample (n = 10,000) to confirm the generalisability of the model developed.
Results:
A bifactor model, also known as the “quadripartite” model, displayed good fit. All scales displayed acceptable fit with the Graded Response Model. Simulation of three unidimensional (depression, anxiety, and stress) CATs resulted in an average 17% to 48% reduction in items administered when a reliability of .80 was acceptable.
Conclusions:
The current study clarifies previous conflicting findings regarding the DASS-21 factor structure and suggests the quadripartite model for the DASS-21 items fits best. IRT modelling suggests that the items measure their respective constructs best between 0 and 3 theta (mild to moderate severity).
Citation
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Copyright
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