Data were analyzed using multivariable linear / logistic regression. Logistic regression was used for the dichotomous persistent conduct problem outcome. Linear regression was used for the continuous hyperactivity scores since this method produced effect sizes which were easier to interpret and potentially more sensitive to genetic and environmental influences. We conducted stepwise regression analyses of adversity on conduct disturbances and hyperactivity in order to identify the most important factors associated with each outcome. An arbitrary 5% significance level was used to select factors. The choice of measures and time-points that were used in subsequent analyses were therefore determined by the associations found in the stepwise regression analyses. Since this is an exploratory study, no corrections were made for multiple testing. Data was analyzed separately for boys and girls since MAOA is an X-linked gene.
