Table 3.
Recommended and observed values of validity criteria for the Swedish WHODAS 2.0, n = 780
| Criterion | Recommended value | Domain 1 | Domain 2 | Domain 3 | Domain 4 | Domain 5 |
Domain 5a n = 780 |
Domain 5b n = 652 |
Domain 6 | All domains |
|---|---|---|---|---|---|---|---|---|---|---|
|
Unidimensionality (PCA of residuals) | ||||||||||
| Variance explained by measures | > 60% | 55 | 54 | 45 | 51 | 66 | 77 | 76 | 57 | 48 |
| Eigenvalue of the unexplained variance in 1st contrast, logits | < 2.0 | 1.6 | 1.6 | 1.9 | 1.6 | 3.9 | 1.6 | 1.9 | 1.6 | 3.8 |
| Disattenuated correlation | > 0.70 | 0.89 | 1 | 1 | 1 | 1 | 0.95 | 0.88 | 0.94 | 0.80 |
| Reliability | ||||||||||
| Cronbach’s alpha | > 0.80 | 0.87 | 0.85 | 0.70 | 0.82 | 0.93 | 0.94 | 0.95 | 0.88 | 0.96 |
| Person reliability | > 0.80 | 0.79 | 0.57 | 0.23 | 0.67 | 0.86 | 0.90 | 0.91 | 0.83 | 0.91 |
| Item reliability | > 0.80 | 0.98 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.96 | 0.99 | 0.99 |
| Person separation, logits | ≥ 2 | 1.91 | 1.14 | 0.55 | 1.43 | 2.53 | 2.95 | 3.14 | 2.22 | 3.18 |
| Item separation, logits | ≥ 2 | 7.99 | 8.15 | 9.75 | 9.68 | 8.44 | 11.60 | 4.70 | 12.56 | 13.08 |
| Targeting | ||||||||||
| Mean person ability, logits* | ± 1 | 1.91 | 2.46 | 2.17 | 1.37 | 1.20 | 2.29 | 1.57 | 0.94 | 1.21 |
| Ceiling effect | ≤ 2% | 11.5 | 31.5 | 37.2 | 14.6 | 12.8 | 19.7 | 19.3 | 4.6 | 2.7 |
| Floor effect | ≤ 2% | 0 | 0.1 | 0 | 0 | 1.2 | 2.2 | 7.4 | 0 | 0 |
| Effective operational range | ≥ 90% | 83 | 58 | 52 | 73 | 78 | 70 | 69 | 92 | 92 |
Deviations from the recommendation are in bold. *Reversed order of rating scale categories: low scores indicate greater difficulty
Domains: D1, Understanding and communicating; D2, Getting around; D3, Self-care; D4, Getting along with people; D5, Life activities; and D6, Participation in society. D5, Life activities, is divided in two areas: D5a = Domestic responsibilities, and D5b = Work and school. (PCA, principal component analysis.)