It s official: having friends of the opposite sex is bad for children s grades
DO FRIENDS of the opposite gender distract teenagers, hampering their academic
performance? It may seem obvious, at least to paranoid parents, and yet it is
hard to prove. Simple analysis of a survey of American schoolchildren conducted
in 1995, for example, suggests no link between the proportion of a girl s
friends who were boys and her grades. Boys with lots of female friends actually
achieved better results than those with fewer.
A new paper* by Andrew Hill of the University of South Carolina, however, digs
deeper into the data, and comes to a different result. Friendship groups are
not random, which makes it tricky to isolate the effect of fraternising with
the opposite sex on school performance. Pushy parents, for instance, may both
encourage after-school activities (hotbeds of hobnobbing across the gender
divide) and help out with homework. By the same token, the sort of boys who do
not find it embarrassing to join a clique composed mainly of girls may also be
more studious.
Mr Hill gets around this by looking at the proportion of schoolmates of either
sex living near each student. He reasons that parents do not choose where to
live based on the sex of their neighbours children. The gender mix of
near-neighbours should therefore be unrelated to the invisible factors that
influence both friends and grades. But the mix of neighbours does influence
friendship groups in school, since children are much more likely to befriend
other children who live close by.
Mr Hill calculates the share of boys and girls among each child s 20 closest
neighbours and uses this to identify random differences in friendship groups.
He can then isolate the effect of having more friends of the opposite gender on
school performance. He finds that for every 10% more children of the opposite
sex among a student s friends, his or her grade-point average (GPA) declines by
0.1 (GPAs range from 0 to 4).
Below the age of 16, the effects are restricted to science and maths, but
beyond 16 they spill over to English and history as well. Girls seem to be more
prone to distraction, though Mr Hill cannot muster the statistical power to be
certain. This tentative result is consistent with other studies that find that
girls gain more from moving to single-sex schools.
Readers rushing to remove their children from co-ed schools should know,
however, that Mr Hill s results came with a twist. Having more friends of the
opposite sex may be bad for grades, but it has other effects, too. Among the
children from the original survey who were successfully re-interviewed 14 years
later, those whose grades had been dragged down by friends of the opposite
gender were more likely to be (or have been) married. Traditionalists worried
about a child mooning over the heartthrob next door may comfort themselves with
that.
achievement , American Economic Journal: Applied Economics, July 2015.