ANN ARBOR—The larger the group, the smaller the chance of forming interracial friendships, a new University of Michigan study shows.

Published in the Proceedings of the National Academy of Sciences, the study examines how the size of a community affects the realization of people’s preferences for friends. U-M researchers Siwei Cheng and Yu Xie tested their theoretical model using both simulated and real data on actual friendships among 4,745 U.S. high school students.

“We found that total school size had a major effect on the likelihood that students would form interracial friendships. Large schools promote racial segregation and discourage interracial friendships,” said Xie, a sociologist with the U-M College of Literature, Science and the Arts, Institute for Social Research and the Gerald R. Ford School of Public Policy.

Their model incorporates the widely held assumption that people prefer to make friends with others of the same race. It also incorporates many other preferences that affect friendship formation. These factors include age, education, hobbies, personality, religious affiliation and political beliefs.

Given these individual preferences, the researchers found that when the size of the social group is small, people have a low likelihood of finding a same-race friend that matches their other preferences. But as the total size of the group increases, people are more likely to find same-race friends who also satisfy their other preferences.

Cheng, a U-M graduate student in sociology, and Xie, who is also affiliated with Peking University, note that their work has implications for other social relationships, such as dating, marriage, political coalitions and business affiliations.

“One potential negative social consequence of the Internet as a social interaction medium in an ever more globalized world is to encourage social isolation and social segmentation by expanding group size immensely,” Cheng said.

Established in 1949, the University of Michigan Institute for Social Research is the world’s largest academic social science survey and research organization, and a world leader in developing and applying social science methodology, and in educating researchers and students from around the world. ISR conducts some of the most widely cited studies in the nation, including the Thomson Reuters/University of Michigan Surveys of Consumers, the American National Election Studies, the Monitoring the Future Study, the Panel Study of Income Dynamics, the Health and Retirement Study, the Columbia County Longitudinal Study and the National Survey of Black Americans. ISR researchers also collaborate with social scientists in more than 60 nations on the World Values Surveys and other projects, and the institute has established formal ties with universities in Poland, China and South Africa. ISR is also home to the Inter-University Consortium for Political and Social Research, the world’s largest digital social science data archive. For more information, visit the ISR website at www.isr.umich.edu.