We have had quite a lot of back and forth on this blog about Boston charter schools, in anticipation of the vote this November in Massachusetts about lifting the charter cap and adding another 12 charter schools every year forever. Pro-charter advocates argue that the Boston charters are not only outstanding in test scores but that their attrition rate is no different from that of the public schools, or possibly even less than the public schools.

Jersey Jazzman (aka Mark Weber) is a teacher and is studying for his doctorate at Rutgers, where he specializes in data analysis.

In this post, he demolishes the claim that Boston charters have a low attrition rate. As he shows, using state data,

In the last decade, Boston’s charter sector has had substantially greater cohort attrition than the Boston Public Schools. In fact, even though the data is noisy, you could make a pretty…