Table 4.
Estimated parameters of NMSQT common factor model for parental education models
| Parameter | Subtest |
||||
|---|---|---|---|---|---|
| English | Math | Social | Natural | Vocabulary | |
| λ | 1.00 | 1.29 | 1.22 | 1.26 | 1.15 |
| δ1 | 9.99 (43.6%) | 20.98 (52.8%) | 5.73 (24.1%) | 13.46 (40.1%) | 6.58 (28.4%) |
| δ2 | 8.93 (43.5%) | 17.52 (44.9%) | 5.56 (23.4%) | 13.07 (40.5%) | 6.18 (27.4%) |
| MZσ2(1,2) | 5.25 | 10.76 | 1.48 | 4.38 | 4.36 |
| DZσ2(1,2) | 4.52 | 6.54 | 0.25 | 3.95 | 2.99 |
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 education model without either interaction term; parameter estimates from other income models differ by less than 0.1