Last week, CREDO, a Stanford University research organization that focuses mostly on charter schools, released an analysis of the test-based effectiveness of charter schools in “urban areas” – that is, charters located in cities located within in 42 urban areas throughout 22 states. The math and reading testing data used in the analysis are from the 2006-07 to 2010-11 school years.
In short, the researchers find that, across all areas included, charters’ estimated impacts on test scores, vis-à-vis the regular public schools to which they are compared, are positive and statistically discernible. The magnitude of the overall estimated effect is somewhat modest in reading, and larger in math. In both cases, as always, results vary substantially by location, with very large and positive impacts in some places and negative impacts in others.
These “horse race” charter school studies are certainly worthwhile, and their findings have useful policy implications. In another sense, however, the public’s relentless focus on the “bottom line” of these analyses is tantamount to asking continually a question ("do charter schools boost test scores?") to which we already know the answer (some do, some do not). This approach is somewhat inconsistent with the whole idea of charter schools, and with harvesting what is their largest potential contribution to U.S. public education. But there are also a few more specific issues and findings in this report that merit a little bit of further discussion, and we’ll start with those.