onset were available for all of the above and they were included as time-varying covariates. Offspring DSM-IV inattention, hyperactivity and oppositional defiant disorder were queried in mother interviews, with two dummy-variables coded to distinguish affected offspring from those with missing parent-report data (18.6 – 21.6% each). Additional family characteristics included as covariates in each final model were maternal DSM-IV AD and history of heavy cannabis use (150+ times lifetime), with a dummy-variable included for cases where mother’s substance history was missing (8.5% for AD, 8.7% for heavy cannabis use), and family income (a set of dummy-variables based on father’s report, <$20,000, $20,000–$100,000, and >$100,000, with the middle income group used as the referent category).
