Math tests are good for you, according to a new study of more than 155,000 Norwegian 16-year-olds who took mathematics or language exit exams between 2002 and 2004. The intense preparations that precede those exams and their high-stakes nature reduce the dropout rate and increase enrollment in higher education, according to new research.

Researchers agree that there’s a connection between math test scores and educational attainment, income, and other individual outcomes, but it remains unclear if math scores are simply an indicator of good things to come or if something about taking a math test and doing well actually brings those good things about. That’s something only a randomized experiment could possibly tell you.

### Preparing for and taking a math exit exam increased boys’ probability of graduating high school within five years by 0.3 percent, while there was even less impact, if any at all, on girls.

Fortunately for economists Torberg Falch, Ole Henning Nyhus, and Bjarne Strøm, Norway’s education system set up just such an experiment.

Throughout Norway, students have 10 years of compulsory education beginning at age six and ending at age 16. When that time is up, they take an exit examination that’s a bit unusual by American standards. First, the test helps determine whether a student will go on to further academic or vocational training. Second, students in Norway take one of three tests, and which one they take is chosen at random. About 40 percent take a mathematics exam, another 40 percent take a Norwegian language test, and the rest take a test on English language, but they don’t know which one until a few days before taking it.

Those few days, in other words, turn into a nation-wide cram session for students and a perfect experiment to test the effects of intense preparation, testing, and math. Falch, Nyhus, and Strøm’s analysis of test data and other education records confirms what researchers had thought—sort of. Each additional day of preparation for the math exam increased the probability of completing high school within five years by about 0.2 percent relative to others and upped the probability of going on to study at a university by a similar amount.

Boys, it turns out, account for most of that effect: Preparing for and taking a math exit exam increased boys’ probability of graduating high school within five years by 0.3 percent, while there was even less impact, if any at all, on girls. Exactly why that is, the researchers write in the journal *Labour Economics*, is unclear, but may be related to prior math skills. When the researchers broke things down further, they found that girls with low math skills benefited as much, if not more than, boys with low and high math skills. Girls who’d already been good at math didn’t seem to benefit from taking the exit exam.