NASHVILLE, Tenn. —Offering middle-school math teachers bonuses of up to $15,000 didn't produce gains in student test scores, Vanderbilt University researchers reported Tuesday, in what they said was the first scientifically rigorous test of merit pay for teachers.
The results could amount to a cautionary flag about paying teachers for the performance of their students, a strategy that the Obama administration and many states and school districts have favored despite lukewarm support or outright opposition from teachers' unions.
The U.S. Department of Education has put a great deal of effort into luring school districts and states to try merit-pay systems as part of its Race to the Top competition, although teachers' unions often have objected on the grounds that they don't have fair and reliable ways to measure performance. In most school districts, teacher pay is based on years of experience and educational attainment levels.
The report's authors, from the National Center on Performance Incentives at Vanderbilt University's Peabody College of Education, stress that more research is needed to determine whether different approaches that link teacher performance to pay or additional training could help boost student achievement.
Matthew Springer, the director of the federally funded center, said pay-for-performance isn't "the magic bullet that so often the policy world is looking for."
At least in this experiment, Springer said, "it doesn't work."
The test was conducted from 2006 to 2009 in partnership with the nonprofit RAND Corp., a research center. A local industrialist and Vanderbilt benefactor, Orrin Ingram, put up the nearly $1.3 million in bonuses.
Some 296 middle-school math teachers in the Nashville school district — two-thirds of the total of middle-school math teachers — volunteered to participate in the experiment. About half were placed randomly in a control group, while the rest were eligible for bonuses of $5,000, $10,000 or $15,000 if their pupils scored significantly higher than expected on the statewide exam known as the Tennessee Comprehensive Assessment Program.
One-third of the eligible teachers — 51 of 152 — got bonuses at least once. Eighteen teachers received bonuses all three years.
Except for some temporary gains for fifth-graders, though, their students progressed no faster than those in classes taught by the other 144 teachers.
The teachers' union in Nashville agreed to the experiment in collective bargaining, according to Erick Huth, the president of the Metropolitan Nashville Education Association. He said the results weren't at all surprising.
"I've believed for a long time that what improves instruction is having an instructional leader who is able to get all players in a school to collaborate," Huth said
The bonuses amounted to a sizable chunk of teachers' yearly salaries in Nashville, where the scale runs from $36,000 to $64,000, Huth said.
The study didn't shake the faith of U.S. Secretary of Education Arne Duncan in merit pay.
"While this is a good study, it only looked at the narrow question of whether more pay motivates teachers to try harder," said Sandra Abrevaya, a spokeswoman for Duncan. It didn't address the Obama administration's push to "change the culture of teaching by giving all educators the feedback they need to get better."
The researchers said the Nashville experiment didn't stir the negative reactions that had attended some other merit pay programs, but it "simply did not do much of anything."
Springer said the study laid a foundation for further experiments on a topic that educators had been debating "for over a century."
Frederick Hess, the director of education policy studies at the American Enterprise Institute in Washington, said he didn't think the study said much of value, and he's concerned that it will only confuse the issue.
"The fact that teachers don't respond to cash bonuses like rats do to food pellets does nothing to diminish my confidence that it's good for schooling if teacher pay better reflects the contributions that teachers make," Hess said.
William Slotnik, the executive director of the Boston-based Institute for Compensation Reform and Student Learning at the Community Training and Assistance Center, said it would take more than financial incentives to improve student achievement and that merit pay "is hard to get right."
"If all you are doing is focusing on money, there is no track record in that resulting in the kind of changes needed to do this work well."