A person trying to choose their next set of wheels might see that car A made it farther than car B in a road test and assume it gets better gas mileage. But that’s only true if the two tanks are filled with the same substance. Putting high-octane gas in one and water in the other, for example, provides little useful information about which car makes the most of its fuel. A new working paper titled “Do Parents Value School Effectiveness?” suggests that parents similarly opt for schools with the most impressive graduates rather than figuring out which ones actually teach best. The study joins a body of research looking critically at what it means for a school to be successful.
Take the work of Erin Pahlke, for example. The assistant professor of psychology at Whitman College saw research showing that girls who attend school only with other girls tend to do better in math and science. The trick, she said, is that those studies didn’t analyze “differences in the students coming into the schools.” As it turns out, those who end up in same-sex schools tend to be wealthier, start out with more skills, and have parents who are more proactive than students who attend co-ed institutions. In a 2014 meta-analysis, Pahlke and her colleagues reviewed the studies and found when examining schools with the same type of students and same level of resources—rather than “comparing [those at] the public co-ed school to [their counterparts at] the fancy private school that’s single-sex down the road”—there isn’t any difference in how the students perform academically. Single-sex schooling also hasn’t been shown to offer a bump in girls’ attitudes toward math and science or change how they think about themselves. In other words, it often looks like single-sex schools are doing a better job educating kids, but they aren't. It's just that their graduates are people who were going to do well at any school. They’re running on high-octane gas.