New Study First to Affirm Value of National Teacher Certification

Published May 1, 2004

For the first time since the National Board for Professional Teaching Standards (NBPTS) came into being in 1987, a large-scale study has found teachers who win its certification “appear to be,” on average, more effective than their non-certified colleagues.

The differences between nationally certified and non-certified teachers, based on “value-added” assessment of their impact on student achievement, were small, but statistically significant.

NBPTS officials and advocates quickly claimed the results prove their national certification system works. Former Georgia Governor Roy Barnes, the current NBPTS chairman, said the study showed the National Board is “the gold standard” in assessing teachers. “The study provides state and national policymakers with proof that National Board Certification is a smart investment,” he said.

But a host of analysts and critics–and even the study’s authors–said the data fall far short of proving NBPTS is a cost-effective way of identifying excellent teachers. Moreover, they note NBPTS certification does nothing to ensure that the best teachers get into schools where they are most desperately needed, and stay there. Nor does the study show there is anything about the certification process itself that improves teachers.

Student Achievement Gains

Titled “Can Teacher Quality Be Effectively Assessed?” the Urban Institute study by Dan Goldhaber and Emily Anthony examined more than 600,000 achievement records of grades 3-5 pupils in North Carolina from 1996 to 1999. North Carolina has 6,641 NBPTS-certified teachers, the most in the nation. The state gives NBPTS-certified teachers a 12 percent premium above the base salary scale, which amounts to an average $4,000 annual bonus.

With respect to student achievement, based on averages, the study found:

  • Teachers who did not apply for NBPTS certification had student achievement gains of 9.75 points per year in math and 5.69 points in reading.
  • Teachers who applied but were unsuccessful showed student achievement gains of 9.14 points in math and 5.83 points in reading.
  • Teachers who applied for and won NBPTS approval recorded student achievement gains of 10.21 points in math and 6.18 points in reading.

“These differences, nonetheless, are relatively small; the largest differential is in math between certified and non-certified teacher applicants, at just over a point on the exam or roughly 14 percent of a standard deviation in the growth in math scores,” the study explained.

Schools May Be Worse Off

While documenting this small positive result, Goldhaber and Anthony acknowledged the large expense of NBPTS: some $350 million in subsidies, excluding the bonuses North Carolina and many other states pay teachers who win the certification after a process largely consisting of self-documenting their teaching style. Is that level of investment worthwhile? The authors said it depends on the subsequent career paths of the National Board Certified Teachers (NBCTs), as well as the impact of teachers using so much time to try to gain the certification.

“Our findings suggest that schools with many unsuccessful applicants or those with successful applicants that leave following their certification may actually be worse off for having had their teachers apply to the program, since NBCTs are no more (or less) effective than non-applicants in the year of application and unsuccessful applicants are less effective in the year of application. Teaching assignment also matters, as schools with NBCTs receive substantially more educational benefits from having their NBCTs teach low-income students in earlier grades.”

Because the study did not show that anything about the certification process itself makes teachers more effective, any economic benefit of identifying NBCTs would depend partly on whether the certification prolongs their stay in teaching, which is unknown. Even assuming that winning the status did lengthen the stay of NBCTs, the cost-effectiveness of identifying them would be less than another vaunted educational intervention that also carries a high price tag, and the net results of which are in dispute: reducing class size.

The National Education Association, the nation’s largest teacher union, joined NBPTS in hailing the results, despite the Urban Institute study’s use of student test scores as a measure of teacher effectiveness. Both the NEA and NBPTS have steadfastly argued against the use of standardized test results as an indicator of teacher quality.

Professor John Stone, the Education Consumers Clearinghouse founder whose 2002 study of Tennessee’s NBPTS-certified teachers found no evidence they are “exceptionally effective,” said “what the Urban Institute study really demonstrated is that ‘value-added’ statistical analysis can identify the highest-performing teachers with far more accuracy and far less cost than the NBPTS certification process.”

North Carolina could save $35 million by omitting the costly and time-consuming NBPTS assessment and simply rewarding teachers on the basis of a value-added analysis of their student test scores, Stone contended.

Teachers Not Exceptional

A key difference exists between Stone’s 2002 study and the current report by the Urban Institute. Stone examined the small number of NBCTs in Tennessee to determine whether any of them would qualify as exceptional teachers using a value-added yardstick under the terms of a teacher awards program currently used in Chattanooga. None did.

The Urban Institute study compared hundreds of NBCTs in North Carolina to determine whether they produced higher achievement gains than the thousands of North Carolina teachers who are not certified by the National Board. They did, but just barely.

The difference between NBPTS-certified and non-certified teachers in North Carolina was so small that few, if any, of the North Carolina NBCTs would have qualified for the Chattanooga award–an award that has been earned by several teachers working in Chattanooga’s low-income, lowest-achieving schools.

To put the Urban Institute findings in perspective, Stone suggested policymakers use the widely known 1996 Sanders and Rivers study as a guide to what truly exceptional teachers are able to do. It found students taught by the top 20 percent of teachers for three consecutive years made substantially higher achievement gains than ones taught by teachers in the bottom 20 percent.

Although differences between the two studies prevent direct comparison, less than 25 percent of the achievement gains produced by North Carolina’s NBPTS-certified teachers would be in the top 20 eprcent of the gains produced by non-certified teachers. In other words, the NBPTS-certified teachers produced very little additional achievement over that produced by most other teachers.

The other 75 percent of the gains produced by NBPTS-certified teachers would fall below the 80th percentile, and two-thirds of these gains would fall below the average achievement gains produced by all non-NBPTS-certified teachers. In other words, rather than being an elite group, NBCTs are not much different from other teachers.

“Is this level of teaching what policymakers intend to reward?” Stone asked. “I think not.”

The Urban Institute study was the first of a series expected to be released following widespread criticism that NBPTS is making little difference in boosting student achievement after 17 years of government and foundation support. Several states are re-evaluating whether giving bonuses for NBPTS certification is a wise use of taxpayer money.

Robert Holland is a senior fellow at the Lexington Institute, a public policy think tank in Arlington, Virginia. His email address is [email protected].

For more information …

The March 5, 2004 Urban Institute study by Dan Goldhaber and Emily Anthony, “Can Teacher Quality Be Effectively Assessed?” is available online at

The statement by J.E. Stone regarding the Goldhaber/Anthony study, “National Board for Professional Teaching Standards (NBPTS): Improving Education at a Snail’s Pace,” is available online at