WASHINGTON — A study released Tuesday found offering teachers annual bonuses of up to $15,000 had no effect on student test scores — a result likely to inflame debate about performance pay programs sprouting in schools nationwide.
The study suggests teachers already were working so hard that the lure of extra money failed to induce them to intensify their effort or change methods of instruction. The experiment, in Nashville public schools, calls into question a key aspect of market-driven initiatives to improve schools that have become vogue in some education circles.
With backing from federal and state governments and private foundations, a growing number of public schools have embraced paying teachers in part on how much they raise student achievement.
President Barack Obama has encouraged the movement despite skepticism from some teachers unions. That is a major shift from the tradition of determining pay by seniority and credentials such as master's or doctoral degrees.
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But the study from the National Center on Performance Incentives at Vanderbilt casts doubt on hopes that performance pay alone can dramatically improve public schools.
In a three-year experiment backed by federal funding, researchers tracked what happened in Nashville when math teachers in grades 5 through 8 were offered bonuses of $5,000, $10,000 and $15,000 for hitting targets in annual test-score gains. About 300 teachers volunteered, and half were assigned to a control group ineligible for the bonuses.
On the whole, researchers found no significant difference between the results from classes led by teachers who received bonuses and those led by teachers who did not.
Obama administration officials were quick to note that the study did not examine the effect of performance pay in combination with other measures to improve teaching.