Many prior studies have found that low-income students have less qualified teachers based on measures such as years of teaching experience, teacher licensure test scores, certification status, and educational attainment, but they say very little about how these differences relate to closing the achievement gap, nor do they examine the magnitude of how differences in access to effective teachers might impact performance.
Yet a new Mathematica study is full of surprises. It examines low-income students’ access to effective teachers in grades four through eight over five years (2008–09 to 2012–13). “Low income” is defined as being eligible for free and reduced-price lunch (FRPL), and “high income” includes everyone else (so not much nuance there). The sample includes twenty-six geographically diverse, large school districts across the country, with a median enrollment of 70,000. And analysts measure the effectiveness of each teacher in the district using a value-added model.
There are five key findings.
First, contrary to conventional wisdom, teachers of low-income students are nearly as effective as teachers of high-income students on average (a difference of one percentile point). Specifically, the average teacher of a low-income student is just below the fiftieth percentile, while the average teacher of a high-income student is at the fifty-first percentile.
Second, high- and low-income kids have similar chances of being taught by the most and least effective teachers. For example, 10 percent of both high and low income kids are taught by one of the top 10 percent of teachers in a district.
Third, teachers hired into high poverty schools are equally effective as those hired into low poverty schools. Though both the new hires are less effective than the average teachers, and high poverty schools have more new hires than low poverty schools, neither makes much of a difference because those differences are already small and the performance of new hires improves fast: on average, they become as effective as the average teacher after one year.
Fourth, not surprisingly, on average, teachers who transfer to schools that are higher in poverty than the one they left are less effective than the average teacher. Yet those differences don’t impact equity much because just under 4 percent of all teachers transfer to schools in a higher or lower poverty category anyway (a little more than 4 percent move between schools with similar poverty rates).
Fifth and finally, teacher attrition doesn’t much affect access to effective teachers among high- and low-income kids because the leavers are equally effective among high- and low-poverty schools. Only in a small subset of districts (three out of twenty-six) did they find inequity in access to effective teachers—and it was in math only. In those three districts, if you provided high- and low-income kids with equally effective teachers from fourth to eighth grade, you’d see a reduction in the student achievement gap by at least a tenth of a standard deviation, which is equivalent to four percentile points over a five-year period.
With all that said, the sample the study uses is not nationally representative, even though it is geographically diverse and mostly includes large districts that are lower performing. It also mirrors the types of achievement gaps we see nationally, including in NAEP performance. Therefore, these findings may not hold in small districts or rural areas, for example.
Furthermore, it’s possible that the poorest children in the country (say, those at the tenth percentile of the income distribution) are in fact getting less-effective teachers than the richest kids (those at the ninetieth percentile, for example). But this study couldn’t examine that question because it relied on a binary definition of socio-economic status (i.e., whether a student was eligible for FRPL or not)—and again, findings are not nationally representative.
Still, analysts conclude with a simple summary: The achievement gap arises from factors other than students’ access to effective teachers.
Given that this bottom line finding is the result of an expensive study commissioned by a federal agency and conducted by a well-regarded research shop, it represents a big debunking of conventional wisdom.
SOURCE: Eric Isenberg et al., “Do Low-Income Students Have Equal Access to Effective Teachers? Evidence from 26 Districts,” Institute of Education Sciences, U.S. Department of Education (October 2016).
