Young in Class: Implications for Inattentive/Hyperactive Behaviour of Canadian Boys and Girls

Using data from the Statistics Canada National Longitudinal Survey of Children and Youth (NLSCY), this paper investigates the impact of school entry age on inattentive/hyperactive behaviours. We employ both a cross-provinces-time differences-in-differences approach, and a within-province regression discontinuity design. We find that being young in class causes greater inattentive/hyperactive behaviour, exacerbating any inattentive/hyperactive behavior exhibited prior to school entry. These results also also hold in sibling fixed effect models. Though we do not find gender differences in the effects, because boys are more likely to be inattentive/hyperactive at school entry, they are more affected. These effects persist into early adolescence