The home and family background of Ottawa public school children in relation to their IQ's

Over a period of 10 years the IQ's of 9956 children in grade 4 of Ottawa public schools were determined, and grouped into 4 categories (below 90, 90-109, 110-129, and above 129). From the 1941 census records information was obtained concerning home and family circumstances. The most striking findings were progressive increases in number of homes owned by the parents, median value of both owned and rented homes, percentage of children living with both parents, median income of father, and schooling of parents, with increasing IQ. More parents of high IQ children were engaged in professional work and fewer in non-skilled labor, in comparison to low IQ groups. There was an inverse relation between IQ and median number of children in the family.