Table 3.
Summary of the Partial credit model results.
| Sub-scales | PCA (a) | PSEP (b) | Infit (c) | Outfit (c) | DIF (d) sex | DIF (d) age |
|---|---|---|---|---|---|---|
| A | 1.9 | 1.83 | Item 2 Item 6 |
Item 2 Item 6 Item 1 |
Item 4 | |
| B | 2.1 | 1.89 | Item 16 Item 20 |
Item 16 Item 20 Item 18 |
Item 20 | Item 16 Item 17 |
| C | 1.7 | 1.99 | – | – | – | Item 23 Item 26 |
| D | 2.1 | 1.82 | – | – | – | Item 38 |
(a) First eigenvalue of the Principal component analysis on residuals; (b) Person separation index; (c) items with infit/outfit statistics out of the range 0.7–1.3; (d) Items with differential functioning for sex or age (adolescents vs. adults).