Social multipliers in sexual initiation decisions among U.S. high school students.

In this article, I use a national sample of high school students to test for several types of social influences on the decision to have sexual intercourse. I find evidence of endogenous social interactions (social multipliers), where the propensity of an individual choosing to have sex varies with the average behavior in his or her school. Additionally, the magnitude of the social multipliers and several other interesting risk factors differ by gender and by race. These findings might help explain the large variation in sexual initiation across schools in the United States. These results also add to the debate over school vouchers and ability grouping because social multipliers imply changes in school-wide rates of sexual behavior with moderate changes in school-body composition. In this way, school vouchers and ability grouping might exacerbate the situation of high rates of teenage pregnancy and out-of-wedlock births in some communities. To show the potential benefits and costs of public policies that cause students to change schools, I present the results of several simulation exercises that predict the school-level changes in rates of sexual initiation following changes in school composition.