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Evaluation Studies of the National Center for Education Evaluation and Regional Assistance

Study of the Distribution of Effective Teaching

Contractors: Mathematica Policy Research, Inc.; American Institutes for Research

Background/Research Questions:

There is a persistent achievement gap in the United States where students from high-income families outperform those from low-income families on achievement tests. There is also substantial variation in the effectiveness of teachers. A key question for policy makers is whether policy initiatives focused on providing low-income students with equal access to effective teachers can address the achievement gap. This study provided information about the extent to which disadvantaged students received less-effective teaching than other students. The study also examined teacher mobility in participating districts and how patterns of mobility might contribute to unequal access.

The study is addressing the following key research questions:

  • Are low-income students taught by less effective teachers than high-income students? If so, to what extent would providing equal access to effective teachers reduce the student achievement gap?
  • Are there differences between high- and low-poverty schools in teacher hiring, transfer, and attrition? If so, are they consistent with inequitable access to effective teachers for low-income students?


The study documented low-income students' access to effective teachers, as measured by value added across the 2008–2009 through 2012–2013 school years. The study also described district polices designed to address inequitable distribution of effective teaching implemented during those years. Lastly, the study examined teacher mobility patterns within participating districts. Annual data collection included district administrative records such as student achievement to conduct value added analyses, as well as annual semi-structured interviews with district leadership to provide information on district policies. District personnel data was also collected to examine teacher mobility within participating districts. The study was conducted in 29 geographically-dispersed school districts.

Cost/Duration: $8,792,648 over 7 years (September 2010–September 2017)

Current Status:

The first report was released in November 2013 (see An evaluation brief, A Summary of Recent IES Research on Access to Effective Teaching, was released in January 2014 (see The final report was released in October 2016 (see

Key Findings:

The final report focused on low-income students' access to effective teachers and teacher mobility patterns in 26 districts and found that:

  • There are small differences in the effectiveness of teachers of high- and low-income students, on average. The average teacher of a low-income student is just below the 50th percentile of effectiveness based on value-added, while the average teacher of a high-income student is at the 51st percentile. Providing low-income students with equally effective teachers would not substantively reduce the achievement gap.
  • In a subset of the study districts, there is meaningful inequity in teacher effectiveness in math. In three of the 26 study districts, providing low-income students with teachers whose effectiveness is equal to that of high-income students over a five year period would reduce the math achievement gap by at least a tenth of a standard deviation of student achievement, the equivalent of about 4 percentile points.
  • Teacher hiring patterns are consistent with small inequities in access to effective teachers. High-poverty schools have more newly hired teachers than low-poverty schools, but this difference is likely to have a small influence on equity because (1) relatively few teachers are new hires (11 percent of teachers in high-poverty schools and 5 percent in low-poverty schools), and (2) performance of newly hired teachers improves quickly. On average, newly hired teachers become as effective as the average teacher after one year.
  • Teacher transfer patterns are also consistent with small inequities in access to effective teachers. Teachers who transfer to schools in a higher poverty category are less effective (43rd percentile) than the average district teacher. Teachers who transfer to schools in a lower poverty category are nearly as effective (48th percentile) as the average district teacher. These patterns likely have a small influence on equity since just under 4 percent of all teachers transfer across poverty categories each year.
  • Teacher attrition patterns do not contribute to inequity. Teachers who leave a district are less effective (44th percentile) than the average teacher and more teachers leave high-poverty schools than low-poverty schools (10 percent versus 7 percent, respectively).