The relation between income,intelligence, education and social background

In this article the authors have tried to estimate the relative importance of education, intelligence and social background for the explanation of the variations in personal income. The investigation has been carried out on Swedish data which were generously made available to them by Professor Husén of Stockholm University.The results pointed to education as the most important factor in explaining the income variations, followed by the social class of the fathers and the level of intelligence in this order. The relations turned out to be strongly curvilinear.Moreover, the interactions between the explanatory variables have been studied. It was found that their combined contribution is much larger than would correspond to additivity, in particular for the higher classes of the variables. They clearly reinforce each other.