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Table 3 Fit of the DASS and HADS items and all subscales (testlets) to the Rasch model

From: Depression and anxiety in patients with rheumatoid arthritis: prevalence rates based on a comparison of the Depression, Anxiety and Stress Scale (DASS) and the hospital, Anxiety and Depression Scale (HADS)

Analysis Subscale Item Fit Residual Person Fit Residual Chi-Square Interaction PSI Uni-dimensionality
   Mean SD Mean SD Value DF P   % tests CI
Depression           
8 DASS-D -0.396 1.541 -0.431 1.244 49.69 28 0.007 0.945 6.59 3.3-9.9
9 DASS-D -0.276 1.567 -0.354 1.132 39.34 22 0.013 0.940 4.79 1.5-8.1
10 HADS-D -0.263 0.872 -0.382 0.899 25.16 28 0.619 0.856 3.01 0.0-6.3
Depression Combined           
11 D+H-D -0.560 1.422 -0.442 1.133 68.82 42 0.005 0.920 12.05 8.7-15.4
12 D+H-D -0.423 1.248 -0.373 1.084 57.31 34 0.007 0.912 7.23 3.9-10.5
Stress            
13 DASS-S -0.025 1.383 -0.425 1.575 41.18 28 0.052 0.949 7.19 3.9-10.5
All Scales combined as testlets          
14 All -0.400 0.729 -0.353 0.842 10.73 10 0.378 0.900 2.52 0.0-5.9
15 All -0.123 0.749 -0.378 0.968 10.12 10 0.430 0.870 2.00 -1.5-5.5
Ideal Fit   0.0 1.0 0.0 1.0    > 0.05* > 0.7 < 5.0 Lower CI below 5
  1. *Bonferroni adjusted