New York City Charter Schools Lift Scores in Nearby Traditional Public Schools

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A new publication released by Temple University analyzes the spillover effects of public charter schools in New York City neighborhoods. The report by Sarah Cordes, titled “In Pursuit of the Common Good: The Spillover Effects of Charter Schools on Public School Students in New York City,” finds evidence that the closer a public charter is to a traditional public school, the higher traditional public school students will score on Math and Language Arts assessments. Cordes is one of the first researchers to tackle how charter schools’ proximity affects academic performance of neighboring traditional public schools, with special consideration given to traditional and charter public schools located in the same building. Charter schools can benefit financially from co-locating with traditional public schools, as it can help alleviate certain facilities, maintenance, and upkeep costs. Cordes wanted to discover whether these blended-style buildings had a symbiotic relationship, or ultimately proved detrimental to students due to resource constraints.

Cordes limited the focus of her research to spillover effects contained within a radius of one mile of each traditional public elementary school by analyzing data from nearly 900,000 students over a 14-year period. In her analyses, Cordes accounted for students transferring between charter and traditional public schools by using an intent-to-treat analysis which assigned students to the initial school they were attending. Contrary to the assertions of many charter school critics, Cordes found that charter proximity had no detrimental impact on nearby traditional public schools. In fact, Cordes found that:

  • The introduction of a charter school within one mile of a traditional public school increased the performance of traditional public school students by 0.02 standard deviations in Math and Language Arts;
  • Traditional public schools that were co-located in the same building with a charter schools experienced performance increases of 0.09 standard deviations in Math and 0.06 standard deviations in Language Arts;
  • Retention decreased between 20-40 percent in traditional public schools located within 1 mile of a charter school; and
  • The effects of co-location were specific to charter schools as traditional public schools that are co-located with each other did not show the same type of gains.

Nearby charter schools seem to enhance academics because they also augment the academic environment around them. Utilizing parent and student surveys, Cordes found that fewer students reported feeling unsafe at a traditional public school that was co-located with a charter school as compared to their peers at standalone traditional public school. Students also report feeling more engaged, while traditional public school teachers reported that charter schools helped to raise overall academic expectations after their entrance. This evidence seems to counteract critics’ claims that charter schools ultimately harm traditional schools by draining necessary resources away from other public school students.

Charter schools are a growing movement in the United States. In 2016-17, charter school served more than 3 million students across the U.S., and their student population has nearly tripled over the past decade. While this study is limited to NYC, it builds on a body of evidence that charter schools are ultimately having small, positive effects on traditional public schools (especially nearby traditional public schools) – contrary to the conjecture of many charter school critics.

Adam Gerstenfeld is a LEE Fellow spending the summer working with the National Alliance's research team. 

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