Developments in 12 outcomes in the three cohorts over a two year period including effect of gender and parental education. The symbols G, S and T stand for Gender, Socioeconomic status/parental educational level, and Time, respectively. The symbols × and – indicate an interaction and negative direction of effect, respectively. An italic symbol indicates a factor with significant effect after stratification for gender. Subscript symbols b and g stand for boys and girls, respectively.