Problems with high stakes, low quality testing

The percentage of students falling below some arbitrary cutoff is a bad statistic to use for management purposes. (Again, this is Statistical QA 101 stuff.) It throws away information. Worse, it creates perverse incentives, encouraging schools to concentrate on the students performing at around the cut-off level and to neglect both those too far below the threshold to have a chance of catching up and those comfortably above it.