Determination of relations between intelligence, social background, school career and occupation, level of occupation and income on the basis of a survey held in 1952 ( by the authorities of the province of Noord-Brabant ) on pupils of 6th grade of primary schools. School career and occupational career from 6th grade of primary school / kind of primary school / family situation / advice from teacher and wish of parents for secondary education / results of tests / for each year: type of education plus results / looking for job, expectations / wishes regarding nr. of working hours / fitting of r's job and r's education / r's position on the labour market / components of income. Background variables: basic characteristics/ household characteristics/ characteristics of parental family/household/ occupation/employment/ income/capital assets/ education/ social class/ religion