A few years ago, the conventional center-left position, espoused by pundits as well as by the Obama Administration itself, was that the way to close the Achievement Gap was to give low-income students equal access to high quality teachers, as measured by Value Added Modeling.
This view has receded among both journalists and the Department of Education (which is instead focusing on important questions like who goes in which bathroom and whether enough students are becoming student activists.) But methodological questions about VAM aside, it’s worth noting that there’s just not good evidence that the gap in teacher quality between low-income and high-income schools even exists.
For example, today a report from 26 districts was released by the Department of Ed, using a common measure of VAM across all kids, high-income as well as low-income. The headline finding:
There are small differences in the effectiveness of teachers of high- and low-income students in the average study district. In both subjects, differences in the effectiveness of teachers of high- and low-income students are one percentile point, on average. The average teacher of a low-income student is just below the 50th percentile, while the average teacher of a high-income student is at the 51st percentile. As a result, providing low-income students with at least equally effective teachers typically would not substantively reduce the student achievement gap. In addition, high- and low-income students have similar chances of being taught by the most effective teachers and the least effective teachers. In ELA, for example, 10 percent of both high- and low-income students are taught by one of the top 10 percent of teachers in a district, while 9 percent of high-income students and 10 percent of low-income students are taught by one of the bottom 10 percent of teachers.
Here is the distribution of VAM-measured effectiveness for Math teachers, for low and high-income:
And for English/Language Arts:
There’s no evidence that low-income districts are having more trouble attracting effective new hires:
And there’s no evidence that low-income districts are more likely to be losing their best teachers to attrition:
This is all good news; I think it’s fair to ask for roughly comparable public services for poor and rich people in the country, even if the measures of teacher quality have some intrinsic flaws. But I’d be a lot happier if we followed Jerry Brown’s (now-retracted) lead, and said that eliminating the achievement gap per se is just not a tractable goal for educational policy, and focused on just making schools better for everybody, to the limited extent that we can.