Table 2.
Power for between-group variable by type of analysis and manipulated factors.
| Variable | Item discrimination | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Low (0.5–0.99) | High (1.5–2) | |||||||||
| ρ | Cluster | N | DIF = 0.4 | DIF = 0.8 | DIF = 0.4 | DIF = 0.8 | ||||
| OLR | HOLR | OLR | HOLR | OLR | HOLR | OLR | HOLR | |||
| 0.05 | 50 | 5 | 0.312 | 0.287 | 0.82 | 0.802 | 0.773 | 0.753 | 1 | 1 |
| 10 | 0.555 | 0.529 | 0.982 | 0.981 | 0.971 | 0.966 | 1 | 1 | ||
| 20 | 0.859 | 0.836 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 100 | 5 | 0.571 | 0.55 | 0.979 | 0.977 | 0.975 | 0.973 | 1 | 1 | |
| 10 | 0.829 | 0.817 | 1 | 1 | 0.999 | 0.999 | 1 | 1 | ||
| 20 | 0.982 | 0.979 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 200 | 5 | 0.83 | 0.816 | 1 | 1 | 0.998 | 0.998 | 1 | 1 | |
| 10 | 0.984 | 0.981 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 20 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||
|
| ||||||||||
| 0.25 | 50 | 5 | 0.305 | 0.284 | 0.812 | 0.787 | 0.763 | 0.746 | 1 | 1 |
| 10 | 0.55 | 0.51 | 0.982 | 0.972 | 0.967 | 0.955 | 1 | 1 | ||
| 20 | 0.835 | 0.807 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 100 | 5 | 0.557 | 0.53 | 0.979 | 0.975 | 0.975 | 0.968 | 1 | 1 | |
| 10 | 0.83 | 0.81 | 1 | 1 | 0.999 | 0.999 | 1 | 1 | ||
| 20 | 0.971 | 0.963 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 200 | 5 | 0.831 | 0.821 | 1 | 1 | 0.999 | 0.998 | 1 | 1 | |
| 10 | 0.985 | 0.983 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 20 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||
|
| ||||||||||
| 0.45 | 50 | 5 | 0.303 | 0.28 | 0.817 | 0.786 | 0.778 | 0.755 | 1 | 1 |
| 10 | 0.534 | 0.487 | 0.983 | 0.976 | 0.971 | 0.964 | 1 | 1 | ||
| 20 | 0.819 | 0.767 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 100 | 5 | 0.551 | 0.525 | 0.98 | 0.977 | 0.974 | 0.969 | 1 | 1 | |
| 10 | 0.831 | 0.796 | 1 | 1 | 0.999 | 0.998 | 1 | 1 | ||
| 20 | 0.974 | 0.954 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 200 | 5 | 0.814 | 0.796 | 1 | 1 | 1 | 1 | 1 | 1 | |
| 10 | 0.979 | 0.969 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| 20 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||