TY  - JOUR
AU  - Kraska, Jake
AU  - Bell, Karen
AU  - Costello, Shane
PY  - 2023
DA  - 2023/6/22
TI  - Graded Response Model Analysis and Computer Adaptive Test Simulation of the Depression Anxiety Stress Scale 21: Evaluation and Validation Study
JO  - J Med Internet Res
SP  - e45334
VL  - 25
KW  - graded response model
KW  - DASS-21
KW  - CAT
KW  - computer adaptive testing
KW  - simulation
KW  - psychological distress
KW  - depression
KW  - anxiety
KW  - stress
KW  - mental health
KW  - screening tool
KW  - tool
KW  - reliability
KW  - development
KW  - model
AB  - Background: The Depression Anxiety Stress Scale 21 (DASS-21) is a mental health screening tool with conflicting studies regarding its factor structure. No studies have yet attempted to develop a computer adaptive test (CAT) version of it. Objective: This study calibrated items for, and simulated, a DASS-21 CAT using a nonclinical sample. Methods: An evaluation sample (n=580) was used to evaluate the DASS-21 scales via confirmatory factor analysis, Mokken analysis, and graded response modeling. A CAT was simulated with a validation sample (n=248) and a simulated sample (n=10,000) to confirm the generalizability of the model developed. Results: A bifactor model, also known as the “quadripartite” model (1 general factor with 3 specific factors) in the context of the DASS-21, displayed good fit. All scales displayed acceptable fit with the graded response model. Simulation of 3 unidimensional (depression, anxiety, and stress) CATs resulted in an average 17% to 48% reduction in items administered when a reliability of 0.80 was acceptable. Conclusions: This study clarifies previous conflicting findings regarding the DASS-21 factor structure and suggests that the quadripartite model for the DASS-21 items fits best. Item response theory modeling suggests that the items measure their respective constructs best between 0θ and 3θ (mild to moderate severity). 
SN  - 1438-8871
UR  - https://www.jmir.org/2023/1/e45334
UR  - https://doi.org/10.2196/45334
UR  - http://www.ncbi.nlm.nih.gov/pubmed/37347530
DO  - 10.2196/45334
ID  - info:doi/10.2196/45334
ER  -