Table 3.
Estimated parameters of NMSQT common factor model for income models
| Parameter | Subtest |
||||
|---|---|---|---|---|---|
| English | Math | Social | Natural | Vocabulary | |
| λ | 1.00 | 1.30 | 1.22 | 1.23 | 1.14 |
| δ1 | 10.15 (44.3%) | 21.36 (53.7%) | 5.40 (22.7%) | 13.56 (40.4%) | 6.52 (28.1%) |
| δ2 | 8.98 (43.7%) | 17.57 (45.0%) | 5.40 (22.7%) | 12.64 (39.1%) | 6.07 (26.9%) |
| MZσ2(1,2) | 5.26 | 10.99 | 1.39 | 4.19 | 4.34 |
| DZσ2(1,2) | 4.57 | 6.44 | 0.15 | 3.86 | 2.91 |
Note: Factor loadings (λ) are equal for Twin 1 and Twin 2, but residual variances (δ1; δ1) allowed to differ. Percentages of unique variance are in parentheses. Residual covariances between Twin 1 and Twin 2 noted as σ2 (1,2). Parameters are estimated from the parental income model without either interaction term; parameter estimates from other income models differ by less than 0.1