Using student-level data, this paper examines the impact of charter schools on the academic performance of students who remain in the local public schools of New York City, instead of joining its rapidly expanding charter sector. In particular, it tests whether there is a relationship between how much math and reading skill a regular public school student has acquired during a school year and the percentage of his or her classmates who left for a charter school at the end of the previous school year, controlling for both observed and unobserved factors pertaining to the student and his or her school. The analysis reveals that students benefit academically when their public school is exposed to competition from a charter. Findings include:
- For every 1 percent of a public school's students who leave for a charter, reading proficiency among those who remain increases by about 0.02 standard deviations, a small but not insignificant number, in view of the widely held suspicion that the impact on local public schools of students' departures for charter schools would be negative.

- Competition from charter schools has no effect on overall student achievement in math.

- In both math and reading, the lowest-performing students in public school benefit from competition from charter schools.

This report by the Center for Research on Education Outcomes (CREDO) at Stanford University found that there is a wide variance in the quality of the nation's several thousand charter schools with, in the aggregate, students in charter schools not faring as well as students in traditional public schools. The report found that the academic success of students in charter schools was affected by the individual state policy environment. This report is the first detailed national assessment of charter school impacts since its longitudinal, student-level analysis covers more than 70 percent of the nation's students attending charter schools. The peer-reviewed analysis looks at student achievement growth on state achievement tests in both reading and math with controls for student demographics and eligibility for program support such as free or reduced-price lunch and special education. The analysis includes the most current student achievement data from 15 states (AR, AZ, CA, CO, FL, GA, IL, LA, MN, MO, NC, NM, OH, TX) and the District of Columbia and gauges whether students who attend charter schools fare better than if they would have attended a traditional public school. This link enables access to the executive summary, full report, technical appendix and press release.

This book aims to inform the policy debate by examining four primary research questions in several geographic locations: (1) What are the characteristics of students transferring to charter schools? (2) What effect do charter schools have on test-score gains for students who transfer between TPSs and charter schools? (3) What is the effect of attending a charter high school on the probability of graduating and of entering college? (4) What effect does the introduction of charter schools have on test scores of students in nearby TPSs?  We examine similarities and differences in the answers to these questions across locations, seeking insights about the policy levers that might be available to improve the outcomes associated with charter schools. Data sets are from Chicago, IL; Denver, CO; Milwaukee, MN;  Philadelphia, PA; San Diego, CA; Florida; Ohio; and Texas.
Authors: Ron Zimmer, Brian Gill, Kevin Booker, Stephane Lavertu, Tim R. Sass, John Witte