4 Things We Don't Know About AP Tests

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This week and next is a national rite of passage for stressed-out overachievers everywhere. Nearly 3 million high school students at 22,000 high schools will be sitting down to take their Advanced Placement exams.

Created by the nonprofit College Board in the 1950s, AP is to other high school courses what Whole Foods is to other supermarkets: a mark of the aspirational, a promise of higher standards and, occasionally, a more expensive alternative.

AP courses promise to be the most rigorous a school has to offer. They can lift your GPA even higher than a perfect 4.0, thanks to the magic of transcript "weighting." And if you spend $93 to take the exam, plus often hundreds of dollars for textbooks and lab fees, they may be exchangeable for college credit.

Recently the AP has boomed. Participation doubled in the last 10 years, and also doubled in the decade before that. The U.S. Education Department's Office of Civil Rights even collects data on who has access to, and enrolls in, AP courses, using it as a measure of educational equity.

But (and you knew there was a 'but' coming), "remarkably little independent research has been conducted on the academic benefits of AP." That's according to Russell T. Warne, an assistant professor of psychology at Utah Valley University, who has done some of that limited research. Part of the problem, he tells NPR Ed, is that, "it's really hard to do causal research because we can't force people to do AP or force them out of it."

Here are just a few important questions experts don't know the answer to:

Anecdotally, it appears that fewer colleges may be accepting AP credit. But Warne says there's no central data collection that would let us know for sure. If you can't get college credit, it removes a major economic motivation for taking the courses.

"Schools and districts have been encouraging more and more students to participate in AP, but there isn't a lot of research on the effectiveness [of that encouragement,] or how the decision is made," says Naihobe Gonzalez, an economist at Mathematica Policy Research. In a recently published paper, Gonzalez looked at thousands of public high school students in Oakland who had scored high on the Preliminary SAT. Their test results included a message that they would do well in an AP course. School records show that most students didn't react. They either didn't notice the message or didn't realize that it was tailored to them specifically. This lack of understanding fits what Gonzalez says is "a pattern of academic mismatch," meaning, "there are students with high test scores who don't enroll in AP and students with lower test scores who do."

But, the study design also suggests a solution. Gonzalez surveyed a smaller group of about 400 high-scoring students face-to-face about their expectations of enrolling in an AP course. The survey may have drawn their attention to the message and the fact that they were likely to succeed in an AP course. These students enrolled in, and passed, an average of one more AP course compared to their equally high-scoring peers.

As more and more students take the tests, pass rates have fallen. This effect happens whenever educational access broadens. "What we don't know is whether there's still value," in taking the course even if you don't pass the exam, says Warne. This is a real-life dilemma for public high schools with low graduation rates and many struggling students. Should they put their best teachers and dedicate precious resources toward offering AP for the extra-motivated few? "That's a very, very hard question," says Warne. "It's not just a scientific question, it's also an ethical question."

One potential boon from taking AP courses — even if you don't pass or get college credit — is non-cognitive. That is, students might thrive on the high expectations, the rigor, the chance to express a special academic interest. Weihua Fan at the University of Houston tried to get at this in a recent study. She found that 10th grade students who were confident at math or science, or found them intrinsically interesting, were more likely to intend to enroll in a math or science AP course. While this result seems fairly intuitive, Fan hopes to show in future studies that this expression of motivation in turn affects people's future success in majoring in STEM in college.

But could this work the other way? If your school doesn't offer as many AP courses, will you be less likely to identify as a strong math or science student and less likely to major in STEM in college? "That's a very good question," says Professor Fan, "but I don't have the answer for it."