Table 3.
Fit of the DASS and HADS items and all subscales (testlets) to the Rasch model
| 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 | |||
*Bonferroni adjusted