The effect of overcrowded housing on children's performance at school

This paper provides estimates of the causal effect of living in an overcrowded home on performance at school in France. Our identification strategy relies on the fact that the size and housing conditions of families vary with the sex composition of the siblings. In particular, large families in which the two youngest children are (by descending age) a boy and a girl tend to live less often in overcrowded housing than the other families. French parents seem to be more reluctant about bringing up their children in the same room when they are not of the same sex, especially when the youngest one is a girl. We build on these results to develop several econometric analyses of the effect of overcrowding on schooling outcomes using variables describing the sex composition of the siblings as instrumental variables. These different strategies reveal that the very strong statistical relationship between housing conditions and academic failure is plausibly one of cause and effect. Children in large families perform much less well than children in small families, but our IV estimates suggest that this is mostly due to the fact that they live in more overcrowded homes.