For nearly 50 years student achievement gap fails to close

For nearly 50 years student achievement gap fails to close

Harvard-Stanford study finds opportunity gap between advantaged and disadvantaged students equivalent to three to four years of learning

March 11, 2019—Differences in the performance on math, reading, and science tests between disadvantaged and advantaged U.S. students have remained essentially unchanged for nearly half a century. In a new article for Education Next, Eric A. Hanushek, Paul E. Peterson, Laura M. Talpey, and Ludger Woessmann report that the achievement gap is as wide today as it was for children born in 1954.

The study contradicts recent insights that socioeconomic achievement gaps have substantially widened in recent years. “After looking at a comprehensive, systematic set of student assessments, we are unable to confirm earlier, more limited research that purports to show income-achievement differences have grown dramatically,” Peterson said.

The authors used a representative sample of student performance data on four national assessments—designed to be comparable over time—administered to students born between 1954 and 2001: both the Long-Term Trend and main versions of the National Assessment of Educational Progress (NAEP); the Trends in International Mathematics and Science Survey (TIMSS); and the Program for International Student Assessment (PISA). The sample includes a total of 98 tests administered to 2,737,583 students over 47 years. The authors examine both the difference in achievement between the highest and lowest 10 percent of the socioeconomic distribution (the 90–10 gap) and the difference between the highest and lowest 25 percent (the 75–25 gap).

Among the key findings:

Extremely disadvantaged students three to four years behind affluent peers. The current gap between the highest 10 percent and lowest 10 percent of the socio-economic distribution (90-10 gap) is roughly three to four years of learning, or more than one standard deviation. Similarly, the current gap between students from the highest 25 percent and the lowest 25 percent of the socio-economic distribution (75-25 gap) amounts to over two-and-a-half years of learning (80 percent of a standard deviation).

Opportunity gap unwavering over last half-century. For students born in 1954, the 90-10 achievement gap was nearly 110 percent of a standard deviation, while for those born in 2001, the gap declined only slightly to one standard deviation. The disparity between students in the top and bottom 25% of the socioeconomic distribution was about 80 percent of a standard deviation for the 1954 birth cohort. This 75-25 gap opened very slightly during the next two decades, only to settle back to barely below 80 percent for the cohort born in 2001.

Gaps between other student subgroups also remain nearly constant. The authors find a persistent achievement gap between students eligible for free and reduced price lunch compared with those who are not eligible. While the Black-White achievement gap did narrow in the early decades of the period under study, it has plateaued for the past quarter century.

Overall performance improves among 14-year-old students over time, but these gains fade by age 17. Performance in math, reading, and science by 14-year-old students has improved steadily on average throughout the past five decades, at roughly 40 percent of a standard deviation, or approximately 8 percent per decade. However, gains among 17-year-old students amount to only about 2 percent per decade and none at all for the last quarter century.

The authors suggest that two off-setting educational developments may have contributed to the unwavering achievement gap. “On the positive side, the country has launched multiple compensatory education programs, including head start, school desegregation, federal aid to districts with low-income students, special education programs, and court-ordered reductions in fiscal inequalities across school districts,” says Hanushek. “On the negative side, we appear to be have seen a decline in teacher quality that has had particularly dire consequences for low-income students.”

To receive an embargoed copy of “The Achievement Gap Fails to Close: Half-century of testing shows persistently wide divide between have-nots and haves” or to speak with the authors, please contact Jackie Kerstetter at The article will be available Monday, March 18 on and will appear in the Summer 2019 issue of Education Next, available in print on May 24, 2019.

About the Authors: Eric A. Hanushek is the Paul and Jean Hanna Senior Fellow at the Hoover Institution of Stanford University. Paul E. Peterson is senior editor of Education Next and professor of government and director of Harvard’s Program on Education Policy and Governance as well as a Senior Fellow at the Hoover Institution. Laura Talpey is a research associate at the Stanford Institute for Economic Policy Research. Ludger Woessmann is professor of economics at the University of Munich.

About Education Next: Education Next is a scholarly journal committed to careful examination of evidence relating to school reform, published by the Education Next Institute and the Program on Education Policy and Governance at the Harvard Kennedy School. For more information, please visit

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