Vanderbilt Researchers on Performance Pay, VAMs, and SLOs

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Do higher paychecks translate into higher student test scores? That is the question two researchers at Vanderbilt – Ryan Balch (recent Graduate Research Assistant at Vanderbilt’s National Center on Performance Incentives) and Matthew Springer (Assistant Professor of Public Policy and Education and Director of Vanderbilt’s National Center on Performance Incentives) – attempted to answer in a recent study of the REACH pay-for-performance program in Austin, Texas (a nationally recognized performance program model with $62.3 million in federal support). The study published in Education Economics Review can be found here, but for a $19.95 fee; hence, I’ll do my best to explain this study’s contents so you all can save your money, unless of course you too want to dig deeper.

As background (and as explained on the first page of the full paper), the theory behind performance pay is that tying teacher pay to teacher performance provides “strong incentives” to improve outcomes of interest. “It can help motivate teachers to higher levels of performance and align their behaviors and interests with institutional goals.” I should note, however, that there is very mixed evidence from over 100 years of research on performance pay regarding whether it has ever worked. Economists tend to believe it works while educational researchers tend to disagree.

Regardless, in this study as per a ResearchNews@Vanderbilt post put out by Vanderbilt highlighting it, researchers found that teacher-level growth in student achievement in mathematics and reading in schools in which teachers were given monetary performance incentives was significantly higher during the first year of the program’s implementation (2007-2008), than was the same growth in the nearest matched, neighborhood schools where teachers were not given performance incentives. Similar gains were maintained the following year, yet (as per the full report) no additional growth or loss was noted otherwise.

As per the full report as well, researchers more specifically found that students who were enrolled in the REACH program gained between 0.13 and 0.17 standard deviations greater gains in mathematics, and (although not as evident or highlighted in the text of the actual report, but within a related table) students who were enrolled in the REACH program gained between 0.10 and 0.05 standard deviations greater gains in reading, although these gains were also less significant in statistical terms. Curious…

While the method by which schools were matched was well-detailed, and inter-school descriptive statistics were presented to help readers determine whether in fact the schools sampled for this study were comparable (although statistics that would also help us determine whether the inter-school differences noted were statistically significant enough to pay attention to), the statistics comparing the teachers in REACH schools versus those not in REACH schools to whom they were compared were completely missing. Hence, it is impossible to even begin to determine whether the matching methodology used actually yielded comparable samples down to the teacher level – the heart of this research study. This is a fatal flaw that in my opinion should have prevented this study from being published, at least as is, as without this information we have no guarantees that teachers within these schools were indeed comparable.

Regardless, researchers also examined teachers’ Student Learning Objectives (SLOs) – the incentive program’s “primary measure of individual teacher performance” given so many teachers are still VAM-ineligible (see a prior post about SLOs, here). They examined whether SLO scores correlated with VAM scores, for those teachers who had both.

They found, as per a quote by Springer in the above-mentioned post, that “[w]hile SLOs may serve as an important pedagogical tool for teachers in encouraging goal-setting for students, the format and guidance for SLOs within the specific program did not lead to the proper identification of high value-added teachers.” That is, more precisely and as indicated in the actual study, SLOs were “not significantly correlated with a teacher’s value-added student test scores;” hence, “a teacher is no more likely to meet his or her SLO targets if [his/her] students have higher levels of achievement [over time].” This has huge implications, in particular regarding the still lacking evidence of validity surrounding SLOs.

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