Table 11.
Changes in the root mean squared error (RMSE) of ability estimates using population and estimated values.
| Condition | Model | RMSE | |
|---|---|---|---|
| Time 1 | Time 2 | ||
| 1 | Two-Class 2PL Mixture IRT | 0.21 | 0.20 |
| Unidimensional 2PL IRT | 0.28 | 0.24 | |
| 2 | Two-Class 2PL Mixture IRT | 0.21 | 0.18 |
| Unidimensional 2PL IRT | 0.28 | 0.26 | |
| 3 | Two-Class 2PL Mixture IRT | 0.21 | 0.18 |
| Unidimensional 2PL IRT | 0.28 | 0.27 | |
| 4 | Two-Class 2PL Mixture IRT | 0.21 | 0.74 |
| Unidimensional 2PL IRT | 0.28 | 0.61 | |
| 5 | Two-Class 2PL Mixture IRT | 0.21 | 0.73 |
| Unidimensional 2PL IRT | 0.28 | 0.63 | |
Simulated with 100 replications using posterior mode estimation. Values in parenthesis represent standard errors.