A new study by Northwestern University researchers for the first time establishes a causal link between the No Child Left Behind Act (NCLB) and improvements in student achievement.

The research finds that NCLB raised math achievement by six to nine months over seven years for the nation’s fourth graders and by four to 12 months for eighth graders. It did not find statistically significant effects for fourth-grade reading achievement. Eighth-grade reading was not assessed because adequate data were unavailable.

“Our study is the first to confirm that NCLB has a statistically significant positive effect on students’ fourth- and eighth- grade math achievement,” said Thomas Cook, sociology professor in Northwestern’s Weinberg College of Arts and Sciences, faculty fellow at the Institute for Public Research (IPR) and co-author of the study.

The study is available at http://www.northwestern.edu/ipr/publications/workingpapers/wpabstracts09/wp0911.html

 There are two major research challenges in determining NCLB effects on student achievement, according to study co-author Manyee Wong. The first is the absence of a control group of students not subject to NCLB, since NCLB applies to all U.S. public school students.

The second challenge stems from each state’s freedom to set its own definition of proficiency. “It’s difficult to evaluate NCLB’s effect on student achievement by simply looking at state tests when the states use different tests and cutoff points to determine if a student is proficient,” said Wong, IPR postdoctoral fellow.
To overcome these challenges, the Northwestern study analyzed NAEP student achievement data in two ways. First, it contrasted the achievement of public school students before and after NCLB with Catholic school students. Second, it contrasted student achievement results before and after NCLB in states using higher proficiency standards with states using lower proficiency standards.  

“The logic of these controls is that Catholic students are largely unaffected by NCLB, and that states using lower standards for making AYP designations have a higher fraction of their schools making AYP,” Ms. Wong said. “As a result, fewer schools in lower standard states implement NCLB-required school reforms,” said Ms. Wong.  

Both sets of analyses show that NCLB raised achievement in fourth- and eighth- grade math on the NAEP test. Public schools did better than Catholic ones after 2002, the year NCLB was enacted; states with higher standards and, as a result, with more failing schools did better than states with lower standards and fewer failing schools.

Results of the high- versus low- proficiency comparison further suggests that for the full force of NCLB to bear on school reform and student performance, all states should be evaluated by the same high standards using the same rigorous tests and proficiency cutoff scores.

While the study only evaluates NCLB’s influence on test scores, this is a central issue for policymakers and educators. “It is important that debates include rigorous scientific evidence of the effectiveness of NCLB since billions of tax dollars have been spent on the program and even more will be spent in the future,” said Ms. Wong.

“The program seems to add stress to teachers’ lives and doubtless has unintended consequences not examined in our study,” Ms. Wong added. “But now there is some evidence that NCLB is effective, and this evidence should be a part of future policy deliberations.”

Cook and Wong are co-authors, with IPR researcher Peter Steiner of “No Child Left Behind: An Interim Evaluation of Its Effects on Learning Using Two Interrupted Time Series Each with its own Non-equivalent Comparison Series.”