It makes intuitive sense: Schools, including charter schools, that aren't required to serve every single kid in a district can be choosier about their students. Maybe, the theory goes, they get better results because they can push out low performers or troublemakers and even discourage disabled students from sticking around.

You can hear that very argument in Jim Epstein's excellent video about charters in Camden, New Jersey, just after the 2 minute mark:

But a new report from the New York City Independent Budget Office (IBO) finds that isn't what is actually happening, at least in the City that Never Sleeps (Except in Geometry Class, Sometimes). The report tracked 3,043 students in 53 charter schools and 7,208 students in the 116 traditional public schools nearest to each charter.

Here's what the IBO, which performs an auditing and scoring function similar to the non-partisan Congressional Budget Office, found:

On average, students at charter schools stay at their schools at a higher rate than students at nearby traditional public schools.

at a rate than students at nearby traditional public schools. Students at charter schools left the city's public school system at the same rate as students in nearby traditional public schools.

In other words, charters probably aren't systematically kicking out fuck-ups. At least not any more often than traditional public schools.

A corollary to the "retention myth" is that charters don't accommodate special needs kids at the same level as public schools, or that they subtly (or not-so-subtly) force out kids who turn out to need extra help. Not so, says the report:

When we consider any student identified as having a disability in kindergarten as a special needs student, these students remained at their charter schools through the 2012-2013 school year at a higher rate than similar students at nearby traditional public schools.

Via Eva Moskowitz's Twitter feed.

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