Gary Rubinstein explores the familiar claim that charter schools in New York City are far superior to public schools, when measured by test scores. The media, especially the newspapers, have said this repeatedly, as if it were a proven fact.

Not so fast, Gary says. he checked out the scores of the city’s charter schools, in relation to their “economic need index,” and compared them to public schools with their economic need index.

Only one charter chain stand out as an outlier: Eva Moskowitz’s Success Academy charters.

Otherwise, the test scores of the charter sector were similar to those of public schools.

Gary concludes:

“It seems pretty clear to me that, on average, the charter schools are not outperforming the public schools, based on how about half of of the charters are above the trend line and half below. Also it is relevant that most of the charters have an economic need index between .7 and .9 while there are a significant number of public schools that have an economic need index above .9. This runs contrary to the charter school supporters who continue to insist that charters serve the ‘same kids’ as the nearby ‘failing’ public school.

“Success Academy are such outliers that I can’t understand why charter supporters who are so focused on test scores are not out there insisting that all charter school resources be sent to expand Success Academy and the ‘yesterday’s news’ charters like KIPP, Democracy Prep, Harlem Children’s Zone, The Equity Project, etc. get shut down for poor performance.”