The more girls in a class, the better the academic performance of both boys and girls, a new study finds.
Researchers in Israel examined student performance in 264 high schools, 395 middle schools, and about 1,000 elementary schools.
They had comprehensive data about academic performance and classroom sex ratios in the high schools from 1993 to 2000. They had similar data for the lower grades from 2002 to 2005—plus detailed surveys from that period about students’ classroom experiences (and some information about teachers’ perspectives).
The researchers took advantage of the natural year-to-year variation in sex ratios in classes, in each school. If those variations were truly random—and the authors determined that they were, through statistical tests—year-to-year shifts in academic performance could potentially be traced to them.
They did find such a link. On a battery of tests taken by Israeli 10th-graders, for example, on which the average score was 69 for girls and 63 for boys, the researchers found that a 20 percentage-point increase in the proportion of girls in a class raised boys’ scores 1.6 points and girls’ 1.3. The effect is modest, to be sure. But it’s on the same scale as other much-debated educational reforms, such as reducing class size, the authors noted.
Based on the student surveys, the authors think they know the causal mechanism: Classrooms with more girls reported fewer disruptions and better student-student and student-teacher relations. Teachers also reported feeling less burned-out when they taught more girls than boys.
The tradeoff was pretty much zero-sum: The fewer boys, the better, all the way down to zero. (The best scenario for a boy, I take it, would be to be the lone male in his class.)
The paper builds on similar findings by the Harvard economist Carolyn Hoxby, in a study of students in Texas schools.
“Mechanisms and Impacts of Gender Peer Effects at School,” Victor Lavy and Analía Schlosser, American Economic Journal: Applied Economics (April)