You’ve heard the claims: charter schools take money and resources from public schools, have little accountability and don’t perform as well as their public school counterparts.

Following the logic, we would tend to believe that where charter schools and public schools are in close proximity to one another or share a building — a practice called co-location which is common in many large cities like New York where real estate is at a premium — the impacts would be even more adverse.

New research conducted by Professor Sarah Cordes of Temple University finds that’s not the case. In fact, the opposite is true. Cordes writes:

…that the introduction of charter schools within one mile of a TPS [traditional public school] increases the performance of TPS students on the order of 0.02 standard deviations (sds) in both math and English Language Arts (ELA). As predicted by theories of competition or information transfers, these effects increase with proximity to the charter school and are largest among student in co-located schools where performance increases by 0.09 sds in math and 0.06 sds in ELA. In addition retention decreases between 20-40 percent in TPSs located within 1 mile of a charter school. School level responses that might explain these positive spillovers included higher per PPE [per pupil expenditure] and changes in school practices such as higher academic expectations, student engagement, and levels of respect and cleanliness at the school, as reported on parent and teacher surveys.

The research by Cordes is the first peer-reviewed study on the subject and appears in the Journal of Education Finance and Policy. Cordes analyzed nearly 900,000 students in grades 3-5 who attended traditional public school in an attendance zone that included a charter school serving at least one of those grades between 1996 and 2010.

In an interview on the study for the Education web site The 74, Cordes said, Just the presence of an alternative does it. It doesn’t really matter how great the alternative is – it’s just the fact that that alternative is there, it’s in the building and people see it every day.

Is there a more powerful argument for competition and choice?