The District of Columbia Public Charter School Board (PCSB) recently released the 2014 results of their “Performance Management Framework” (PMF), which is the rating system that the PCSB uses for its schools.
Very quick background: This system sorts schools into one of three “tiers," with Tier 1 being the highest-performing, as measured by the system, and Tier 3 being the lowest. The ratings are based on a weighted combination of four types of factors -- progress, achievement, gateway, and leading -- which are described in detail in the first footnote.* As discussed in a previous post, the PCSB system, in my opinion, is better than many others out there, since growth measures play a fairly prominent role in the ratings, and, as a result, the final scores are only moderately correlated with key student characteristics such as subsidized lunch eligibility.** In addition, the PCSB is quite diligent about making the PMF results accessible to parents and other stakeholders, and, for the record, I have found the staff very open to sharing data and answering questions.
That said, PCSB's big message this year was that schools’ ratings are improving over time, and that, as a result, a substantially larger proportion of DC charter students are attending top-rated schools. This was reported uncritically by several media outlets, including this story in the Washington Post. It is also based on a somewhat questionable use of the data. Let’s take a very simple look at the PMF dataset, first to examine this claim and then, more importantly, to see what we can learn about the PMF and DC charter schools in 2013 and 2014.