Table 2.
Model fit for sets of tests of varying length.
| Test set | Test items (per individual test) |
||
|---|---|---|---|
| S-22 | S-24 | S-25 | |
| Number of unique items | 16 | 16 | 17 |
| Number of common items | 6 | 8 | 8 |
| Fit statistic (item–trait interaction) | 311.01, p = 0.688 | 370.1, p = 0.097 | 456.1, p = 0.0002 |
| Item location, mean (SD) | 0.00 (1.18) | 0.00 (1.46) | 0.00 (1.43) |
| Item fit residual, mean (SD) | −0.11 (0.88) | −0.12 (0.97) | −0.10 (1.07) |
| Person location, mean (SD) | −0.98 (1.31) | −1.14 (1.31) | −1.09 (1.28) |
| Person fit residual, mean (SD) | −0.14 (0.74) | −0.13 (0.60) | −0.12 (0.60) |
| Misfitting items | 0 | 1 × p < 0.01 | 3 × p < 0.01, 1 × p < 0.001 |