The 60 charter schools operating in New York City have provided a unique opportunity for the New York City Charter Schools Evaluation Project, of which we are a part, to conduct a randomized field trial of the impact of charter schools on student achievement. The study reported here thus differs from virtually all other published research on charter schools in its reliance on experimental methods to determine the schools' effectiveness. In particular, we take advantage of the lottery-based admissions process for charter schools to compare the academic performance of two groups of students: those who wanted to attend a charter school and were randomly admitted and those who wanted to attend but were not admitted and remained in traditional public schools. In this article, we present findings from the first year of what will be a multiyear study.
We address two main questions about charter schools in the city. First, who enrolls in New York City's charter schools? And, second, how well are the schools educating students? What we found is that, compared with other students in the traditional public schools, charter school applicants are more likely to be black and poor but are otherwise fairly similar. We also found that charter school students benefit academically from their charter school education. Charter school students in grades 3 through 8 perform better than we would expect, based on the performance of comparable students in traditional public schools, on both the math and reading portions of New York's statewide achievement tests. There is not yet a sufficient number of charter school students in grades 9 through 12 for us to report achievement effects for this group.
Forty-seven charter schools were operating in New York City in the 2005-06 school year, the most recent for which we have test-score results, and all but five are included in the analysis presented here. Two schools, Manhattan Charter School and South Bronx Charter School for International Cultures and the Arts, are participating in our ongoing study but are not included in the analysis because they do not yet have any students in test-taking grades. One school, Read-Net Bronx Charter School, was in the process of closing in 2005-06. The absence of ReadNet Bronx from our evaluation is likely to have only a small impact on our assessment of student achievement because the school had only two years of test-taking students before it closed. The New York Center for Autism Charter School is not included in the study because it serves a very special population and is not compatible with many elements of the study. The United Federation of Teachers Elementary Charter School has declined to participate in the study so far, but it does not yet have any students in test-taking grades.
Charter schools must advertise their availability to all students eligible to attend public schools and are not allowed to select their students from among applicants. Instead, if a charter school in New York receives more applicants than it has places, it must enroll students based on a random lottery. Each spring, charter schools that are oversubscribed hold admissions lotteries.
Our study data are collected as follows: First, the information from each charter school application is sent to the New York City Department: of Education for inclusion in its administrative database. This database contains entries for all students who attend New York City's traditional public schools and for all students who attend New York City's charter schools. A contractor for the department uses the maximum amount of information possible--for example, the student's name, birth date, and Social Security number, if available--to match each applicant to a corresponding existing entry in the department's database. The contractor then extracts information on each student's demographic characteristics, enrollment, test scores, and certification for and participation in various programs such as free and reduced-price lunch, special education, and English-language services. …