It’s well known that college-educated workers earn more money, on average, than those with just a high school diploma. And there are few middle-class jobs available for workers without a degree, as I found in a recent data analysis.
So does that mean more people should go to college?
The Fordham Institute’s Mike Petrilli is skeptical. Many people who don’t attend college “were nowhere near college ready at the end of high school,” he wrote in response to my piece. Sending academically underprepared students to college does them no favors, Petrilli continues. Only 40% or so of high school students have demonstrated college readiness, he says. Pushing the other 60% to college could just lead them to debt without a degree.
I was curious about this myself. Should college be limited to those who do relatively well in high school? To get a better sense, I dug into the research. The findings surprised me.
It is genuinely complicated to determine the value of college and who should attend. While degreed workers make more money, we don’t know if that’s because they went to college.
Fortunately, researchers have developed a clever strategy to see whether four-year college makes a difference: tracking students who just managed to get into college and comparing them to similar peers who didn’t get that opportunity.
An influential 2014 study by Yale University economist Seth Zimmerman focused on Florida International University, a large four-year public college that provided a sharp admissions advantage to students whose GPAs were above 3.0. Zimmerman compared students right above and right below that threshold. The intuition is that someone with a 3.01 GPA is essentially identical to someone with a 2.99 average, except one person receives an admissions edge and the other doesn’t. This creates a natural experiment.
The students who just managed to get into FIU were not academic standouts — far from it. Their SAT scores, just over 800 out of 1600, were at the 21st percentile of high school seniors planning to attend college. For many, if they didn’t get into FIU, they wouldn’t have gone to a four-year college at all.
Zimmerman found a clear advantage for students who got the opportunity to attend FIU. Roughly a decade later, those students earned 22% more than similar students who didn’t get in. These earnings gains were well worth the cost of tuition.
Only about half of these marginal FIU students went on to earn a bachelor's degree within six years. By comparison, the national graduation rate for four-year nonprofit colleges is roughly two-thirds. The study isn’t able to distinguish the effects on graduates versus non-graduates. It can only speak to the average effect. It’s possible that many non-graduates did not benefit or were even harmed. But they may have developed skills in college that helped them in the future, even though they didn’t earn a degree.
This was one paper in one particular setting, but the findings have shown up in other contexts too.
A Georgia study found students who just got into the state’s four-year public university system eventually earned 17% more annually by age 30 than similar non-admitted students. These were students at about the 30th percentile of SAT performance.
Research in Massachusetts found that low-income students who just got into state colleges there received large economic benefits years later. In high school, these students’ test scores were slightly below the average for high school graduates.
A Texas paper, using test-score admissions cutoffs across 35 public colleges, found a clear economic edge for students who won admission to a four-year school.
These studies generally look at students who otherwise would have attended a two-year college rather than no college at all. A different Texas study showed a clear hierarchy: Students fared better in four-year colleges than two-year schools, but a two-year program was better than no college at all. The two-year college advantage was for students at roughly the 30th percentile of high school test performance in the state. (One wrinkle: Another recent study in the state found marginal students didn’t seem to benefit from transferring to a four-year college from a two-year school.)
This body of research should be interpreted with some degree of caution. It looks at specific places and specific groups of students, who typically entered college decades ago. The papers find positive effects on average, but they don’t imply that everyone benefited. The studies can’t speak to whether AI will change the value of a degree, as some predict. The research also doesn’t show whether students are developing skills in college that help them succeed or whether they are getting hired because employers use a college education as a signal of skill.
Still, these papers find that even students who don’t excel in high school often stand to gain from attending college. Many, perhaps most, of these students would not have been categorized as “college ready” by traditional benchmarks. If anything, the research suggests that some states have set college admissions cutoffs that are too high, not too low.
“Given the population of people who want to go, we would benefit from helping more of them go, at least somewhat,” says Zimmerman, the Yale professor.
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