Another fine example for evidence-based policy making

Anyone recall one of the reasons why that NYT piece on charter schools was so horribly unfair? One fine whine goes like this:

Only One Set of Test Scores. Because only one year of information is available for charter schools from NAEP, the study provides test scores for only one point in time. But without better background information, accurately measuring school effectiveness requires information on student performance from at least two points in time.

But wait. Let's be fair. I see we have an article discussing how charter schools fare over a period of time, complete with an example.

Hmmm. Interesting. Looks like this school does worse over time, in comparison to public schools.

According to scores released by the state Aug. 16, the San Francisco Unified School District posted overall gains on standardized tests this year.

But among the schools that actually fared worse was that same Noe Valley school: Edison Charter Academy. When averaged, the scores in all subjects were either stagnant or slightly lower, and certain grades showed precipitous drops.

For those who support evidence-based policy making, here's an example you should use.

Wait, I forgot about this detail. We can no longer conduct statistically sound analyses to see how well charter schools do well over a period of time because the DOE has decided not to collect enough data.

Reference