A $1,000 tuition increase at four-year nonselective public institutions is associated with a 4.5 percent drop in campus diversity among full-time freshmen, according to researchers at Princeton University and New York University.

But tuition hikes at nearby private institutions led to an increase in student diversity at public institutions in the same area, according to the research published in the journal Research in Higher Education.

The study, conducted by Drew Allen of Princeton and Gregory Wolniak of NYU, examined the relationship between tuition prices and racial/ethnic diversity at all U.S. public two- and four-year colleges and universities from 1998 to 2012.

In recent years, tuition at public colleges and universities has risen steadily as states have cut appropriations for higher education. Previous research shows that tuition hikes push enrollments down, but Allen and Wolniak wanted to know whether rising costs also affected student body diversity.

“Jumps in public college tuition drive down the racial and ethnic diversity of the student body, and this effect is particularly strong at the nonselective public colleges and universities that serve as the gateway to higher education for many families,” said Allen, executive director of the Initiative for Data Exploration and Analytics (IDEAS) for Higher Education at the Woodrow Wilson School of Public and International Affairs.

Allen and Wolniak used data from the U.S. Department of Education’s Integrated Postsecondary Education Data System to group students at each campus into six racial/ethnic categories: American Indian or Alaskan Native, Asian, black or African American, Hispanic, white, and other. To measure institutional diversity, they created a modified version of U.S. News & World Report’s diversity index, which expresses the likelihood that two students chosen from a college or university at random will share the same race or ethnicity. In Allen and Wolniak’s index, an institutional score of zero would mean that every student on campus shared the same race or ethnicity. The highest possible score, 100, would indicate an even distribution of students across the six categories.

Notably, a falling diversity index score following a tuition hike didn’t indicate that any particular racial or ethnic group was becoming more or less represented on a campus. Rather, it showed that the campus was becoming more homogeneous, meaning that students there were becoming less likely to encounter peers with backgrounds different from their own.

Allen and Wolniak found the effects of the tuition hikes at public institutions to be more pronounced among full-time freshmen as compared to the overall full-time campus population, and weaker at more selective public institutions that can potentially offer more generous aid packages.

In light of extensive evidence that interacting with peers from diverse backgrounds has strong educational and developmental value, Allen said, the study’s findings “should be cause for concern for all students, particularly those who attend less selective institutions.”

“Our study draws attention to specific factors that might contribute to the racial/ethnic diversity of college at a time when affirmative action and equity in admissions are at the forefront of postsecondary policy discussions,” Allen said.

The study, “Exploring the Effects of Tuition Increases on Racial/Ethnic Diversity at Public Colleges and Universities,” was published March 23, 2018, on the journal’s website.