Table 2.
Fit Parameters of the VILL Questionnaire With 68 Items (VILL-68), the VILL Questionnaire Without Misfitting Items (VILL-37), the Reading Scale (20 items), the Mobility Scale (13 items) and the Emotional Scale (4 items) Compared With Rasch Model Requirements
| Parameters | Rasch Model Requirements | VILL-68 | VILL-37 | VILL –Reading and Accessing Information | VILL – Mobility and Safety | VILL –Emotional Well-Being |
|---|---|---|---|---|---|---|
| Misfitting items, n | 0 | Items 40, 50, 51, 52, 39, 64, 68 | Items 49, 18, 8, 16, 3, 44 | None | None | All items < 0.7 |
| PSI | >2.0 | 4.2 | 3.55 | 2.68 | 2.03 | 1.13 |
| PR | >0.8 | 0.95 | 0.93 | 0.88 | 0.80 | 0.55 |
| Difference in person and item mean | <1 | 0.52 | 0.29 | 0.85 | 0.75 | 0.74 |
| Variance by the first factor | >50% | 47.3% | 44.7% | 53.9% | 54.9% | 68.4% |
| PCA (eigenvalue for 1st contrast) | <2.5 | 5.95 | 4.5 | 2.6 | 2.5 | 1.5 |
| Differential item functioning (Item number [DIF contrast]) | < 1.0, P < 0.05 | |||||
| Gender | na | None | None | None | None | |
| Age group (< 75 to ≥ 75) | na | None | None | None | None |
na = not assessed.