Grading Schools

A new report from the General Accounting Office [PDF] compares privately managed public schools with the traditional variety in six cities and finds mixed results. Students at the privately managed schools score better on standardized tests in Denver and San Francisco, but no better or even significantly worse in four other cities.

Now, I don't particularly have a dog in this race: I think programs of parental choice are apt to improve schools over time, but I can't work up all that much enthusiasm for mere outsourcing that's still mediated by the political process. Nevertheless, it had been my impression that it was often the schools in the worst shape that were passed off to private management. Assuming that's the case here, then shouldn't we be more interested in a longitudinal performance study of each school than a cross-sectional snapshot of the region two or three years after the private firms came in?