This study conducted Rasch analysis of the Depression, Anxiety and Stress Scale using responses of 400 participants to produce ordinal-to-interval conversion algorithms not available to date. Minor modifications such as removing the non-fitting item 5 and combining subscales items into super-items were necessary to achieve the best model fit (χ2(15) = 20.28, p = 0.16). The results support internal validity of the modified 20-item Depression, Anxiety and Stress Scale and include ordinal-to-interval conversion tables for use with non-clinical populations that improve reliability and precision of the measure.
AllenMJYenWM (1979) Introduction on to Measurement Theory. Monterey, CA: Brooks/Cole.
2.
American Psychiatric Association (2013) Diagnostic and Statistical Manual of Mental Disorders: DSM-5 (5th edn). Washington, DC: American Psychiatric Association.
3.
AndrichDHagquistC (2015) Real and artificial differential item functioning. Journal of Educational and Behavioural Statistics37(3): 387–416.
AntonyMMBielingPJCoxBJ, et al. (1998) Psychometric properties of the 42-item and 21-item versions of the Depression Anxiety Stress Scales in clinical groups and a community sample. Psychological Assessment10(2): 176–181.
6.
BondTGFoxJC (2007) Applying the Rasch Model: Fundamental Measurement in the Human Sciences (2nd edn). Toledo, OH: The University of Toledo.
7.
BrogdenHE (1977) The Rasch model, the law of comparative judgment, and additive conjoint measurement. Psychometrika42(4): 631–634.
8.
ChristensenKBMakranskyGHortonM (2016) Critical values for Yen’s Q3: Identification of local dependence in the Rasch model using residual correlations. Applied Psychological Measurement41(3): 179–194.
9.
CrawfordJRHenryJD (2003) The Depression Anxiety Stress Scales (DASS): Normative data and latent structure in a large nonclinical sample. British Journal of Clinical Psychology42(2): 111–131.
GustafssonJE (1980) Testing and obtaining fit of data to the Rasch model. British Journal of Mathematical and Statistical Psychology33: 205–233.
12.
HenryJDCrawfordJR (2005) The short-form version of the Depression Anxiety Stress Scales (DASS-21): Construct validity and normative data in a large non-clinical sample. British Journal of Clinical Psychology44(2): 227–239.
13.
HillEMBillingtonRKrägelohCU (2014) Noise and diminished health: Testing moderators and meditators of the relationship. Noise & Health16(68): 47–56.
14.
KrägelohCUBillingtonDRHsuPH-C, et al. (2016) Ordinal-to-interval scale conversion tables and national items for the New Zealand version of the WHOQOL-BREF. PLoS ONE11(11): e0166065.
15.
LeungYYPngMEConaghanP, et al. (2017) A systematic literature review on the application of Rasch analysis in musculoskeletal disease – A Special Interest Group Report of OMERACT 11. The Journal of Rheumatology41(1): 159–164.
16.
LovibondSHLovibondPF (1995) Manual for the Depression Anxiety Stress Scales (2nd edn). Sydney, NSW, Australia: Psychology Foundation of Australia.
17.
Lundgren-NilssonÅTennantA (2011) Past and present issues in Rasch analysis: The Functional Independence Measure (FIM™) revisited. Journal of Rehabilitation Medicine43: 884–891.
18.
Lundgren-NilssonÅJonsdottirIHAhlborgG, et al. (2013) Construct validity of the Psychological General Well Being Index (PGWBI) in a sample of patients undergoing treatment for stress-related exhaustion: A Rasch analysis. Health and Quality of Life Outcomes11: Article no. 2. DOI: 10.1186/1477-7525-11-2.
19.
MedvedevONSiegertRJKerstenP, et al. (2017) Improving the precision of the five facet mindfulness questionnaire using a Rasch approach. Mindfulness8: 995–1008.
20.
NorquistJMFitzpatrickRDawsonJ, et al. (2004) Comparing alternative Rasch-based methods vs raw scores in measuring change in health. Medical Care42(1): I25–I36.
21.
RaschG (1961) On general laws and the meaning of measurement in psychology. In NeymanJ. (Ed.), Proceedings of the 4th Berkeley symposium on mathematical statistics and probability (pp. 321–333). Berkeley, CA: University of California Press.
22.
SheaTLTennantAPallantJF (2009) Rasch model analysis of the Depression, Anxiety and Stress Scales (DASS). BMC Psychiatry9(21): 2–10.
23.
SiegertRJTennantATurner-StokesL (2010) Rasch analysis of the beck depression inventory-II in a neurological rehabilitation sample. Disability and Rehabilitation32(1): 8–17.
24.
StuckiGDaltroyLKatzJN, et al. (1996) Interpretation of change scores in ordinal clinical scales and health status measures: The whole may not equal the sum of the parts. Journal of Clinical Epidemiology49(7): 711–717.
25.
Szabo’M (2010) The short version of the Depression Anxiety Stress Scales (DASS-21): Factor structure in a young adolescent sample. Journal of Adolescence33(1): 1–8.
26.
TennantAConaghanPG (2007) The Rasch measurement model in rheumatology: What is it and why use it? When should it be applied, and what should one look for in a Rasch paper?Arthritis and Rheumatism57(8): 1358–1362.
