While often outshone by more prestigious higher-education institutions, community colleges actually enroll more than a third of all U.S. undergraduate students and serve as a first point of entry for millions of college-going adults. For more than 40 percent of low-income college students, community colleges are their first higher education experience.

Developmental courses, which are also known as remedial education courses, are a growing concern for researchers and advocacy groups because data shows students are much less likely to complete college if they take even one such class. These developmental courses are mandatory for students who want to earn degrees, but don’t count toward the number of credits they must earn to satisfy graduation requirements. They also cost money, meaning students may feel stymied by coursework that adds to their debt loads but doesn’t move them closer to earning a degree.

Remediation is most prevalent at community colleges, where more than two-thirds of the students are estimated to take such a course, largely because they took a test that found their math or English language skills to be lacking. But a bevy of studies suggest remediation courses themselves hold students back from succeeding in college. One research trick scholars use to determine the effect a program has on students is comparing those who were a few points apart from each other on a remediation exam. The approach, called regression discontinuity (RD), assumes that students who have similar scores also have virtually identical skill sets, even those that scored a few points below the cut-off point that determines whether they’re placed in remedial courses.

Scholars then track these two sets of students as they make their way through college. A Columbia University review of such studies in 2014 concluded that “developmental education has mostly null and sometimes negative effects on student outcomes for students near the cutoffs. . . suggesting that students spent time and tuition on courses that may have made no discernable difference in their ability to succeed in college.”

“So much can go wrong on the day of a placement test. You can have a stomachache and all of a sudden you’re on a remedial track for your first year of college,” said Michelle Asha Cooper, president of the Institute for Higher Education Policy. “There can be a variety of reasons for why you didn’t do well on your placement test. One can be, yeah, I need to be in remedial, and the other can be, ‘I just had a bad day and didn’t do it well.’ I think that colleges and universities have to figure out the right way to assess students’ readiness.”

And despite the importance of these placement tests, the University of Texas survey found that just 41 percent of students study for these assessments.