Table 4.
Rasch item fit statistics of three overfitting and redundant items (comparison between GRSM and PCM)
| GRSM | Item label | PCM | ||||||
|---|---|---|---|---|---|---|---|---|
| INFIT | OUTFIT | INFIT | OUTFIT | |||||
| MNSQ | ZSTD | MNSQ | ZSTD | MNSQ | ZSTD | MNSQ | ZSTD | |
| 0.58 | −2.0 | 0.36 | −0.9 | hitch up trousers | 0.68 | −1.6 | 0.39 | −0.8 |
| 0.48 | −4.0 | 0.33 | −2.1 | place object above head | 0.48 | −3.9 | 0.33 | −2.1 |
| 0.39 | −1.5 | 0.05 | −1.5 | light switch | 0.35 | −1.6 | 0.05 | −1.5 |
GRSM, Grouped Rating Scale Model; PCM, Partial-Credit Model; MNSQ, Mean Square; ZSTD, Standardised Z-score; SD, standard deviation.