It’s nearly school report card time in Ohio. One thing to watch for when examining school performance is whether there are conflicting ratings. For the 2013-14 school year, schools will receive ratings along up to ten dimensions of performance, though no overall letter grade. For example, one might observe a school that receives an “F” on the state’s performance index but at the same time, also receives an “A” on the state’s value-added rating. Or vice-versa. How in the world can this happen?
Keep in mind that these two key ratings—a school’s performance index and value-added—are not the same. The performance index is an indicator of raw student achievement, weighted across a continuum of achievement levels. Value-added, on the other hand, is a statistical estimate of a school’s impact on student progress—expressed as learning gains—over time. Although both measures are based on state test scores, they are different creatures: Achievement tells us more about how students perform; value-added provides evidence on how a school performs (i.e., the productivity of the school staff).
Hence, to understand the quality of a school, we really need both measures. Outside observers—parents, taxpayers, and others—should know whether a school’s students, on average, possess literacy and numeracy skills—that’s achievement. And they should know whether a school is contributing to learning over time—that’s progress.
Now back to the question of mixed ratings. How many schools in Ohio have conflicting results, particularly of the low-achievement but high-progress variety?...