The Academic Impact of Enrollment in International Baccalaureate Diploma Programs

BACKGROUND: In schools accredited as "IB World Schools" by the International Baccalaureate Organization (IBO), teachers use IB curriculum and pedagogy to teach a range of courses that are intended to prepare IB-enrolled students for college. Over the past 18 years, the number of U.S. schools that implement IB programs has increased nearly tenfold, from 133 in 1994 to 1,390 in 2013. Despite the IB program's rapid expansion, little is known about whether IB enrollment causally improves students' academic outcomes, including their high school academic achievement, probability of high school graduation and/or subsequent probability of college enrollment. PURPOSE: This study examines whether enrollment in the IB Diploma Program increases students' academic achievement as measured by their composite ACT college admissions examination scores, probability of high school graduation, and probability of college enrollment, and whether the estimates differ by gender. SETTING, POPULATION, & DATA: This study uses data on the demographic characteristics, IB enrollment status, ACT scores, high school graduation status and college enrollment status of 20,422 students attending 13 Chicago Public Schools (CPS) high schools from 2002-2008. Data sources include the CPS and the National Student Clearinghouse. RESEARCH DESIGN: The analytic strategy is to first assume students are selected into the IB Diploma Program based on their observed characteristics, and then to use a propensity score approach to estimate the impact of IB enrollment on three measures of students' academic success. The second step, following Rosenbaum (2002), is to test the sensitivity of the estimates to different levels of selection bias. RESULTS: This study shows that IB enrollment increases students' academic achievement, probability of high school graduation and probability of college enrollment. Though selection bias may contribute to overstating the propensity score estimates, the conclusion from the sensitivity analyses is that it is unlikely that this internal-validity challenge negates the principal finding. All estimates are greater for boys than for girls. Calculations demonstrate that the IB Diploma Program is a cost-effective way to increase high school graduation rates. CONCLUSIONS: The results are valuable for three reasons. First, they provide valuable information with which to make decisions about future investments in IB. Second, they contribute to knowledge of the means through which to improve high school education for disadvantaged urban youth. Finally, the results suggest that IB enrollment is especially beneficial for boys, for whom the probability of graduating from high school and enrolling in college—in CPS and at the national level—is substantially less than for girls.