The black-white achievement gap. Everyone knows about it; no one seems to know what to do about it. The gap closed a bit in the late 1970s and early 1980s, but then progress stalled. Some have called it “the greatest civil rights issue of our time,” but there’s no agreement about the cure.

Enter economist Roland Fryer. Fryer came from about the most disadvantaged background imaginable, with a mother who left his family and an abusive father who was sent to prison. Fryer has described himself as a “full-fledged gangster” in his teenage years (though his criminal activities, selling marijuana and counterfeit purses, wouldn’t be out of place among any number of college kids).

But Fryer excelled at high school sports, and went to college on an athletic scholarship. It was there, at the University of Texas at Arlington, that he discovered his true passion was not athletic, but academic. Thus began a meteoric rise that saw Fryer earn a Ph.D. in economics, and go on to collaborate with some of the world’s top economists — Nobel winner Gary Becker, “Freakonomics” author Steven Levitt, and many others. He got a job as a Harvard professor, received tenure at the age of 30, and now holds an endowed chair.

Last week, he won the John Bates Clark medal, the most prestigious award given to young economists. He is the first African-American to win the prize. Not bad, eh?

Fryer was (and is) determined to get to the bottom of the achievement gap. Ever since the start of his career, he has fearlessly attacked the problem, not shying away from political incorrectness, bringing a variety of sophisticated research strategies to bear.

One question Fryer has addressed is what causes the achievement gap. Along with Levitt, he found something very interesting. In kindergarten, the black-white gap can be entirely explained by a small number of variables, including socioeconomic status. But as the kids got older, a new racial gap appeared that wasn’t explained by those factors. That means that some other force is at work — education, discrimination, cultural factors or something else.

Fryer set about trying to find those factors. For example, many have long argued that black culture discourages intellectual achievement, by branding academic pursuits as “acting white.” Along with co-author Paul Torelli, Fryer investigatedthe hypothesis. If academics are really considered “acting white,” then it stands to reason that getting good grades should be negatively correlated with popularity. Using data from a survey that asked students who their friends were, Fryer and Torelli constructed a measure of how popular each student was among members of his or her own race (the index is constructed so that having more popular friends confers more popularity than having less popular friends). The results fit the predictions of the “acting white” hypothesis — as students get older, the correlation between grades and popularity goes up and up for white kids, but down for black kids.

An alternative hypothesis, of course, is that racial discrimination is the cause of the black-white achievement gap. Many teachers, if asked, will tell you that this is the case (though they will probably deny that the discrimination comes from their own classrooms!). It’s a very hard thing to measure. But, as Fryer and others have documented, racial discrimination has become less and less important in the U.S. employment market. That doesn’t prove that discrimination isn’t still the culprit at the grade school level, but it is suggestive.

Fryer’s work on the achievement gap isn’t limited to the causes — he has also analyzed a wide range of potential fixes. For example, there’s the idea — intuitive to economists, but usually dismissed by wider society — of simply paying students to do better. Fryer conducted a large number of randomized controlled trials (the gold standard of social research) and found that while paying students for results doesn’t work, paying them to work hard does get results.

What about charter schools? Fryer conducted a study of the Harlem Children’s Zone, one of the most ambitious efforts to close the achievement gap, which uses charter schools and other community programs. Encouragingly, the program managed to close the achievement gap entirely in elementary school, and close the mathematics gap (though not the English studies gap) in middle school. Charter opponents often dismiss charters’ performance as a result of selection effects — if they only select elite or motivated students, of course charters will show good performance. But Fryer eliminates this criticism with a number of statistical techniques. One of these, for example, is to limit his sample to students who got into the schools by winning an admissions lottery, and comparing them to students who lost the lottery. Sure enough, the schools’ success at closing the achievement gap isn’t due to selection effects — it’s real.

Taken all together, Fryer’s work suggests that educational investments, improved motivation and cultural change have a good shot at closing the stubborn achievement gap between black and white students. That isn’t going to please education reform opponents such as Diane Ravitch, who denigrate charters and pooh-pooh the idea that better education could close the gap. It’s also not going to please a lot of conservatives, who typically oppose funneling more resources into government-funded education.

But Fryer’s message — that the achievement gap isn’t invincible, that it can be slain by better education — is backed up by solid data and sophisticated empirical techniques. Those who deny Fryer’s conclusions will have a very hard time refuting the Clark Medal winner’s research.

If we apply his lessons, we’ll move closer to a future when many more kids can make the transition Roland Fryer made — from disadvantaged background to academic excellence. But even then, few will do it in as spectacular a fashion as Fryer himself.