Even with the U.S. Supreme Court having upheld the right of colleges to consider race in admissions decisions, researchers continue to consider what would happen to college demographics if affirmative action vanished.

A new study says that the results would be dramatic -- a 35 percent drop in the enrollment of students from underrepresented minority groups at the most competitive colleges. The study was conducted by business school professors, using economic as much as educational analysis, and suggests that the drop might not have all of the results desired by critics of affirmative action.

The study -- financed by the MacArthur Foundation and the National Science Foundation -- has been published in the Journal of Public Economic Theory. The authors are Dennis Epple, the Thomas Lord Professor of Economics at the Tepper School of Business of Carnegie Mellon University; Richard Romano, the Gerald L. Gunter Professor of Economics at the University of Florida; and Holger Sieg, professor of economics at the Tepper School.

Their approach was based on examining patterns in the admission of students nationally by colleges of different levels of competitiveness, past behavior of colleges when faced with difficulties attracting minority students, and the paper qualifications of minority high school students who could apply to college. While the study acknowledges the flaws inherent in dependence on standardized test scores, it uses SAT and ACT scores (and colleges' patterns of admissions offers) as a measure of students' academic competitiveness.

The researchers traced enrollment patterns not only by race and ethnicity, but by SAT score. If affirmative action is eliminated, the study found, there would be an increase in minority average SAT scores among less competitive colleges because some students who would otherwise have gained admission to competitive colleges would enroll elsewhere.

Perhaps more surprisingly, the researchers predict that the end of affirmative action would lead to a net decrease in average SAT scores among all student groups in the most competitive colleges. The reason for this prediction is that the researchers' analysis of the past behavior of colleges suggests that they would not abandon their quest for a critical mass of minority students, and would seek other ways to preserve what education leaders see as the educational benefits of diversity. As a result, the researchers say, colleges would turn to other measures -- such as zip code analysis, with preference for those from low income neighborhoods -- to try to admit more minority students.

These "inefficient approaches" to replacing affirmative action, the authors write, would result in the admission of more students of all races with lower SAT scores. As a result, the elite colleges would end up losing minority students with higher SAT scores than those that might be admitted in the future, the study says.