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Another Study Shows that Teacher Performance Pay Doesn’t Raise Test Scores

Thursday September 23, 2010

Teacher performance pay has taken another battering from a new study published this week. It demonstrates that the Gillard Government’s plan to pay cash bonuses to the best performing teachers in Australia is unlikely to improve student results and will be a complete waste of money.

A scientifically controlled experiment in the Nashville school system shows that paying large cash bonuses to teachers as a reward for improving student results doesn’t actually generate larger increases in students’ test results. The study is claimed to be the most rigorous study of performance-based teacher pay ever conducted in the United States.

Leader of the study, Professor Mathew Springer from the National Centre on Performance Incentives at Vanderbilt University in Nashville, said pay-for-performance is not “the magic bullet that so often the policy world is looking for”. [ Hechinger Report, 21 September 2010]

The study was conducted over the 2007-2009 school years with participation by mathematics teachers in grades 5-8 in metropolitan Nashville public schools. Nearly 300 teachers, approximately 70 percent of all middle-school mathematics teachers in Nashville’s public schools, volunteered to participate.

The study was designed by researchers from the National Centre on Performance Incentives and the RAND Corporation. About half the teachers were randomly assigned to the treatment group eligible for bonuses of between $5,000 and $15,000 each based on whether their students’ achievement increased by a specified amount over the course of a year. The other half were not eligible for bonuses.

Teacher performance was calculated by using a value-added model, which predicts how students will do in a given year based on how they performed in the previous year. The teachers had to hit the 80th and 90th percentiles to receive the $5,000 and $10,000 bonuses, respectively, while the $15,000 bonuses were paid to teachers whose students performed at a level that historically had been reached by only the top 5% of middle school mathematics teachers.

After three years, there were no significant differences between the two group’s results. On average, students taught by the teachers taking part in the program did not make larger gains than those taught by teachers in the normal pay group. In addition, there were no significant differences in any single year, nor were there significant differences for students in grades 6-8 when separate effects were estimated for each grade level.

The study also found little evidence that pay incentives induced teachers to make substantial changes to their instructional practices or their level of effort in the classroom.

The sole exception to the overall results was in grade 5 in the second and third years of the study. In those years, the incentive pay was linked to statistically significant increases in student scores  an increase equal to between a third and a half year of learning. But the effect did not carry over into 6th grade when the students were tested again; that is, it made no difference to grade 6 test scores whether a student’s 5th grade teacher was in the treatment group or the control group.

The researchers performed a number of tests to try to make sense of the grade 5 findings, including whether there was evidence of a reallocation of time from other subjects to math, or cheating on the tests. But none of them turned up any firm explanation. The study hypothesized that because 5th grade teachers are more likely to instruct the same set of students in multiple subjects it is possible that they achieve better understanding of their students and enjoy greater rapport with them.

Other scholars involved in the study of performance-based pay and teacher incentives have widely praised its rigorous design. “It’s a really well-designed study, and it’s really important because a lot of the debate about performance pay has been evidence-free,” said Steven Glazerman, a principal researcher at Mathematica Policy Research which has also published studies of performance pay [ Education Week, 21 September 2010].

The new study adds to the growing weight of evidence that teacher performance pay fails to increase student test results. Performance pay programs implemented in recent years in Iowa and Texas and in the Chicago and Denver school districts have all been evaluated recently and found not to have increased student results. Schools and teachers participating in these programs did not achieve any higher results than comparable schools or teachers not participating in the programs.

The results of these studies are a major challenge to the Gillard Government’s plan to pay cash bonuses of up to $8000 to about 25,000 of the best teachers, starting in 2014. They suggest that the $1.25 billion program is likely to be a complete waste of money.

The new Assistant Treasurer, Bill Shorten, recently pledged to a national statistics conference that the Gillard Government would “rely heavily on evidence-based policy”.

We have heard all this before. Back in 2007, the then Prime Minister promised evidence-based policy. Julia Gillard as education minister promised evidence-based education policy, but major initiatives such as My School were adopted without regard to the lack of evidence to support them.

The cash bonuses for teachers policy is yet another faith-based education policy. If the Gillard Government were at all serious about its renewed pledge for evidence-based policy cash bonuses for teachers would never get off the starting block.

Trevor Cobbold

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