To examine the validity of the scores for the 2 genetic factors and 1 shared environmental factor, 2 types of analyses were performed. First, separate regressions for these 3 factor scores were conducted to evaluate differences in the magnitude of the association with each outcome variable. Second, we examined whether we could constrain regression coefficients for all 3 factor score variables to be equal in predicting each outcome variable. The robust weighted least-squares mean- and variance-adjusted estimator in Mplus version 6.024 was used to obtain estimates for these models. In this approach, probit regression coefficients are estimated for each of the genetic factor score variables. Since the estimated genetic factor scores are calibrated on a uniform standard scale, the effect size units are more readily interpretable when comparing coefficients across the different factor score variables. Age was treated as a nonnormal continuous variable and fit using the MLR estimator in Mplus.
