** Reprinted here in the Washington Post
Former Florida Governor Jeb Bush was in Virginia last week, helping push for a new law that would install an “A-F” grading system for all public schools in the commonwealth, similar to a system that has existed in Florida for well over a decade.
In making his case, Governor Bush put forth an argument about the Florida system that he and his supporters use frequently. He said that, right after the grades went into place in his state, there was a drop in the proportion of D and F schools, along with a huge concurrent increase in the proportion of A schools. For example, as Governor Bush notes, in 1999, only 12 percent of schools got A's. In 2005, when he left office, the figure was 53 percent. The clear implication: It was the grading of schools (and the incentives attached to the grades) that caused the improvements.
There is some pretty good evidence (also here) that the accountability pressure of Florida’s grading system generated modest increases in testing performance among students in schools receiving F's (i.e., an outcome to which consequences were attached), and perhaps higher-rated schools as well. However, putting aside the serious confusion about what Florida’s grades actually measure, as well as the incorrect premise that we can evaluate a grading policy's effect by looking at the simple distribution of those grades over time, there’s a much deeper problem here: The grades changed in part because the criteria changed.