Want girls to do better in school? Surround them with smart classmates.

The search for better economic policy.
May 12 2010 7:04 AM

The Right Kind of Peer Pressure

Want girls to do better in school? Surround them with smart classmates.

High school girls.
Smart classmates encourage high school girls

In 1995, clinical psychologist and therapist Mary Pipher rose to national prominence with the publication of Reviving Ophelia, a runaway best-seller that described the many perils confronted by girls coming of age in America. Pipher wrote that around junior high, "many confident, well-adjusted girls were transformed into sad and angry failures." Pressures from teachers, parents, and especially peers were producing a generation of eating-disordered, substance-abusing, academically underachieving girls.

Two recent studies suggest that Pipher's basic observation about girls' vulnerability to peer pressure remains true, but they emphasize that peer pressure can sometimes be a good thing. The studies examined the academic achievement of high school students and found that being surrounded by underachieving classmates has a negative effect on girls and boys—both genders feel pressure to conform to the lower standards of their peers. But the studies also show that girls are more sensitive than boys to the presence of high-achieving peers. Surround a girl with diligent classmates, and her performance will improve.

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There are two basic challenges that have confounded social scientists' efforts to analyze how we're influenced by our peers. First, our peers don't drop from the sky—we tend to associate with others who are like us to begin with or those whom we'd like to emulate. Friends may pressure friends to do drugs, or friends may become friends because they share a rebellious streak that involves doing drugs. Friends also tend to read the same magazines, shop at the same stores, attend the same classes—so if they act the same, it may not be because they pressure each other, but because they are both swayed by the same influences. Economists refer to this as the reflection problem: If two people are moving in tandem, is the left one mimicking the right or vice versa? Or is some invisible force moving both simultaneously?

Researchers have had to get creative to try to overcome the reflection problem. One recent study by Cornell economist Kirabo Jackson measures peer influences by taking advantage of the peculiarities of the high school assignment process in his home country of Trinidad. Testing starts early for Trinidadian children, who take placement exams in fifth grade to determine where they will study through to high school graduation. While students get to rank schools based on location and other preferences, for the most part high scorers attend the best schools in Trinidad and low scorers attend vocational schools. This means that high-scoring fifth-graders will end up in well-funded schools surrounded by other high-scoring students and taught by the island's best teachers. So they tend to go on to do well on their standardized tests at the end of high school. But the quality of each class at any given school will vary from year to year for idiosyncratic reasons: It was a particularly competitive year; new school buses opened up different school choices. As a result, two students who have the same incoming test scores but who are a year apart may end up at the same school with the same teachers and the same financial resources, but with very different peers.

Jackson obtained the school records of more than 150,000 Trinidadian students entering sixth grade between 1995 and 2002 and followed them through to graduation in 10th grade, when all students again take a set of standardized exams. He found that students who attended high school with high-achieving peers performed better at graduation, passing more of their final exams than students who went to the same school in a different year, when the crop of classmates was weaker. Intriguingly, the effect of high-achieving peers was much more positive for girls than for boys. Jackson's results suggest that boys may, in fact, pass fewer exams when surrounded by high-achievers, while girls' graduation exam pass rates are helped by having bookish classmates. While the overall effects are modest—a girl in a strong class might pass one-tenth more exams than if she had been in a weaker one—it appears to be several times stronger for girls enrolled in Trinidad's best schools. (Even boys seem to get a small boost from good peers at these top schools.)