Yesterday I noticed Dylan Matthews of the Washington Post and Matt Yglesias of Slate tweeting that there is proof education reform is working. They cited this set of charts of NAEP score improvements since 1996, posted by Mac LeBuhn, a policy analyst at Democrats for Education Reform. 

I hate to be a downer, but attributing this good news to recent reform pushes, like No Child Left Behind, Race to the Top, and new teacher accountability schemes is extremely iffy, just as Stephen Sawchuck of Ed Week pointed out. Here's why: It just so happens that we have NAEP scores since 1971, and in the area of 8th grade math, which LeBuhn highlighted, the increase in raw scores and reduction of the achievement gap is actually a longterm trend. Take a look:

In fact, achievement gaps shrunk much faster during the 1970s and 1980s than they have over the past decade, essentially because of skyrocketing performance from black children while white children remained relatively stagnant. Was this because of education reforms predominant back them, like school desegregation? Or because of demographic changes, since a more diverse group of students with more challenging backgrounds take the exam today? There are endless hypotheses, but no proof that any one kind of reform, or even reform itself, has led to these changes.