Pearson chi-square analysis showed that HC had significantly higher parental socioeconomic status (SES) than both patient groups, which did not differ from each other (p=.62). Thus, after ruling out group differences in the slopes of the relationships between parental SES and each of the GBR measures (Group x parental SES interaction: total power: p=.75; evoked power: p=0.79; PLF p=0.76) and dropping the interaction terms, Group x Site ANCOVAs were performed on each of the GBR measures using parental SES as a covariate. The parental SES effect was not significant for any of the GBR measures (total power: p=.29; evoked power: p=0.65; PLF: p=0.92), and the Group effects were essentially the same as those resulting from the ANOVA models described above.
