When people discuss academic attainment and disadvantage it tends, implicitly or explicitly, to be about economic disadvantage. This makes sense since socio-economic status (SES) is all too important a predictor of how young people do in the education system. But there are other dimensions worth thinking about.
One is family structure, which is generally understood to refer to which parents, if any, a child is living with. Using PISA data for Ireland, I graph the average reading score by a measure of family structure.
The four categories are “single”: living with a single parent or guardian (usually the mother), “nuclear” : living with mother & father, “mixed” : living with either a mother & male guardian (like a stepfather) or father/female guardian and “other”.
It is clear that children in nuclear families do best. The difference is statistically significant. While there are no controls here, the result is indeed robust when one allows for SES, the child’s sex and various other factors. This isn’t surprising as there is a fair amount of research on this matter looking in particular at the effects of single parenthood on childrens’ outcomes, for example the work by Sara McLanahan and Gary Sandefur.
One has to be very careful about jumping to policy recommendations from evidence such as this. It doesn’t follow that any particular family structure is “best” and people in non-nuclear families are often there for a good reason. What I think can be argued is that our educational system should take account those factors which are known to militate against young people achieving their full potential.
The data here was collected in 2000 but the same pattern would almost certainly show up in more recent waves of PISA or indeed any data on student achievement.