follow-up (rmales=0.40, z=2.46, p=0.01; rfemales=0.41, z=2.035, p=0.04). However, the effect size, as indicated by Cohen’s d, was small (dmales=0.29, dfemales=0.26), with those who did not complete the 17-year-old assessment endorsing only slightly more substances at age 14 than those who did complete the later assessment (males: Mattrition=1.69, Mreturn=1.29; females: Mattrition=1.52, Mreturn=1.10). These statistics suggest that although attrition may at first glance appear notable, any existing differences are small and thus unlikely to impact the results presented here.
