Teachers are scrutinized at their every turn for their impact on students, but it’s not always as easy to turn that spotlight on principals.
For one thing, their connection with students—and the students’ academic progress—seems far more tenuous and indirect. A successful school generally has a successful leader, but just how important a principal is to a student’s accomplishments has mostly been left to conjecture and anecdotes.
A new study from Education Next, however, proves that effective principals make a huge difference when it comes to growth in student achievement. “To me [this study] was a bit surprising because I never thought that principals were that important,” says one of the study’s authors, Eric A. Hanushek, in an interview with TakePart. “But these results suggest that principals have a really big influence on what goes on in schools. And we should pay more attention to principals than we have in the past.”
The study’s results are fairly astounding: “Our results indicate that highly effective principals raise the achievement of a typical student in their schools by between two and seven months of learning in a single school year; ineffective principals lower achievement by the same amount,” writes Hanushek and his co-authors, Gregory F. Branch and Steven G. Rivkin.
“These impacts are somewhat smaller than those associated with having a highly effective teacher,” the authors continue. “But teachers have a direct impact on only those students in their classroom; differences in principal quality affect all students in a given school.”
For their study, the authors took administrative data from the University of Texas at Dallas (UTD) Texas Schools Project and the Texas Education Agency. Over many school years, this project has examined students, teachers, and principals and their quantifiable math achievement. From this, the Education Next study specifically looked at 7,420 elementary and middle school principals in Texas public school from 1995-2001. The authors separated the principals into two groups, those in their first three years of teaching and those with more years under their belt.
The biggest challenge, the authors wrote, was trying to determine a principal’s contributions apart from other student achievement factors, such as poverty or affluence.
“Our basic value-added model measures the effectiveness of a principal by examining the extent to which math achievement in a school is higher or lower than would be expected based on the characteristics of students in that school, including their achievement in the prior year,” Branch, Rivkin and Hanushek write in the study. “Put another way, it examines whether some schools have higher achievement than other schools that serve similar students and attributes that achievement difference to the principal. This approach is very similar to that employed in studies that measure teacher quality using databases tracking the performance of individual students over time.”
Even the most conservative estimates find that good principals make a difference—and so do bad principals.
The authors also discovered that, the stronger the principal, the more likely less-effective teachers were to leave the school. This shows that an effective principal is managing teacher quality and exerting this influence with school-wide results. “A highly effective principal tends to be selective in turnover,” Hanushek says. “He or she will, in fact, keep the better teachers and get rid of the worst teachers. That’s one of the mechanisms that’s important for principals.”
Hanushek says this study will hopefully lead to more research to answer such questions as where the teachers who are dismissed by effective principals end up and how the labor market for principals operates.
“These are huge impacts,” says Hanushek, who is also a senior fellow at the Hoover Institution of Stanford University. “Even the most conservative estimates find that good principals make a difference—and so do bad principals.”
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Kristin Kloberdanz is a freelance writer based in the San Francisco Bay area. She has written for Time, the Chicago Tribune and Forbes.com about everything from economic crises and political snafus to best summer beach reads.