of alcohol use and problems and years of education (as an index of social class), which is known to be associated with AD.34 To determine if the genetic factor scores differed from each other in their prediction of the external validators, two regression analyses were performed. First, separate regressions were conducted to examine the pattern of differences in prediction for each validator. Second, a model constraining the three genetic regression coefficients to be equal within each validator variable was specified. As the outcome variables were binary or ordinal (or rescaled to be ordinal), the robust weighted least squares mean and variance adjusted estimator in Mplus version 6.035 was used to optimize models. This model estimates probit regression coefficients for each of the genetic factor scores. As the estimated genetic factor scores are calibrated on a uniform standard scale, the effect size units are more readily interpretable when comparing coefficients.
