Pupils of teachers certified by the National Board for Professional Teaching Standards (NBPTS) improved an average of 7 percent more on their year-end math and reading tests than pupils whose teachers attempted but failed to gain the certification.
And, the study found that nationally certified teachers bestowed even greater benefits on younger and lower-income students.
"Our findings show that these teachers are more effective," said Dan Goldhaber, a research associate professor at the University of Washington's Evans School of Public Affairs and affiliated scholar of the Urban Institute. He will present the results Friday at the American Education Finance Association annual meeting in Salt Lake City.
The study – funded by the U.S. Department of Education and based on an analysis of more than 600,000 North Carolina elementary test scores – could put to rest some of the controversy in education circles surrounding the national certification.
Since the mid-1990s, more than $350 million has been spent on NBPTS certification, without clear research showing whether the more effective teachers were getting certified.
To find out, Goldhaber and co-author Emily Anthony of the Urban Institute analyzed 610,338 year-end test scores of North Carolina third, fourth and fifth graders from 1996-97 to 1998-99. Each student was matched up with that year's teacher.
Even after factoring out such characteristics as experience, degree level and scores on licensing exams, teachers who met national certification criteria gave their students a small but statistically significant edge over students taught by unsuccessful NBPTS applicants.
And NBPTS teachers' performance advantage was found to be largest for younger and low-income students. For instance, in reading, it rose to 12 percent for the youngest students in the study (third graders) and to 15 percent for low-income pupils.
These results are consistent with decades of research showing that teacher quality has the strongest impact on students in economically disadvantaged students.
One policy implication, Goldhaber said, would be a call for school districts to do more to entice their nationally certified teachers into classrooms with younger and more disadvantaged students.
The NBPTS program was launched 17 years ago by school reformers seeking a way to identify and reward excellent teachers. Applicants undergo an evaluation that includes written exams, portfolios and teaching videos, and fewer than half of North Carolina's applicants succeed on their first try. Critics have said there is no proof all this effort guarantees classroom superiority. Despite the controversy, NBPTS has certified more than 32,000 teachers across the nation, and the number of applicants continues to rise.
Previous attempts to measure these teachers' effectiveness relied on relatively small samples, but Goldhaber and Anthony drew on test scores from three grade levels of an entire state to document that the assessment process does select for teaching skills that actually help children learn.
"Our research does not show that the assessment process itself makes teachers better," Goldhaber said, "but it does appear useful in identifying who the more effective teachers are."
The question is whether identifying the best teachers is worth the assessment program's costs, which NBPTS says amount to more than $200 million in public and private funds to develop the program. Another $150 million has been spent across the nation to assess teachers, and millions has gone to bonuses and raises for those who attain national certification.
"Whether the cost is worth it depends on many factors," Goldhaber said, "not least of which is whether receiving NBPTS certification helps to keep effective teachers in the classroom – particularly in classrooms that need them the most."
For more information, contact Goldhaber at 206-685-2214 in Seattle, or March 10-12 in Salt Lake City by cell phone 206-679-1867. His e-mail address is dgoldhab@u.washington.edu. The study is available online from the Center on Reinventing Public Education at www.crpe.org It is also on the Web site of the Urban Institute, a nonprofit, nonpartisan research organization in Washington, D.C., at www.urban.org. More information about the National Board and NBPTS certification can be found at www.nbpts.org.