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'Research was demonstrably flawed'... Review challenges value of 'value added' claims just as Duncan, major districts expand its use

A major review of the research supporting claims that teachers can be effectively evaluated using something widely referred to as "Value Added" measurement has been challenged again by careful review of the research. The so-called "Value Added" method of evaluating teachers is at the heart of programs in Los Angeles, Chicago, and other cities, and has also been the centerpiece of the legislation proposed in December 2010 by Advance Illinois and Stand for Children to radically change the method Illinois school districts use to evaluate teachers. A dramatic publication of the ratings of Los Angeles teachers by the Los Angeles Times in August 2010 resulted in national headlines about the method (and the death of one Los Angeles teacher who was rated as a "bad" teacher).

But a closer look shows that "Value Added" has little or no real value and is based on flawed research and questionable interpretation of that research. The new report, entitled DUE DILIGENCE AND THE EVALUATION OF TEACHERS... A REVIEW OF THE VALUE-ADDED ANALYSIS UNDERLYING THE EFFECTIVENESS RANKINGS OF LOS ANGELES UNIFIED SCHOOL DISTRICT TEACHERS BY THE LOS ANGELES TIMES was released on February 9, 2011, by the National Education Policy Center (NEPC) at the University of Colorado, Boulder.

"Derek Briggs and Ben Domingue at the University of Colorado at Boulder released a review of the research used in the LA Times value-added project on February 9, 2011," says Jim Horn of School Matter. "It's definitely worth reading and sharing with others. The review disputes the finding that teacher qualifications have no association with student outcomes, looks at the issue of non-random assignment and how the biases the model, and discusses the (im)precision of the model used."

The authors of the NEPC study conclude:

Causal inference may well be the holy grail of quantitative research in the social sciences, but it should not be proclaimed lightly.When the causal language of teacher "effects" or "effectiveness" is casually applied to the estimates from a value-added model simply because it conditions on a prior year test score, it trivializes the entire enterprise. And instead of promoting discussion among parents, teachers and school administrators about what students are and are not learning in their classrooms, it seems much more likely to shut them down.

The two page summary of the report states as follows:

The research on which the Los Angeles Times relied for its teacher effectiveness reporting was demonstrably inadequate to support the published rankings. Using the same L.A. Unified School District (LAUSD) data and the same methods as the Times, Derek Briggs and Ben Domingue of the University of Colorado at Boulder probed deeper and found the earlier research to have serious weaknesses making the effectiveness ratings invalid and unreliable.

Last August, the Times published the results of a “value added” analysis of student test data, offering ratings of elementary schools and teachers in the LAUSD. The analysis was conducted by Richard Buddin, a senior economist at the RAND Corporation, as a project independent of RAND itself." He found significant variability in LAUSD teacher quality, as demonstrated by student performance on standardized tests in reading and math, and he concluded that differences between “high-performing” and “low-performing” teachers accounted for differences in student performance.

Yet, as Briggs and Domingue explain, simply finding that a value-added model yields different outcomes for different teachers does not tell us whether those outcomes are measuring what is important (teacher effectiveness) or something else, such as whether students benefit from other learning resources outside of school. Their research explored whether there was evidence of this kind of bias by conducting what researchers call a “sensitivity analysis” to test whether the results from the L.A. Times model were valid and reliable.

The results of this new critical review of the research adopted and published by the L.A. Times are troubling: with each test of sensitivity, Briggs and Domingue found that Buddin’s approach came up short.

They first investigated whether, when using the Times model, a student’s future

teacher would appear to have an effect on a student’s test performance in the past — something that is logically impossible and a sign that the model is flawed. They found strong evidence of these illogical results when using the L.A. Times model, especially for reading outcomes: “Because our sensitivity test did show this sort of backwards prediction, we can conclude that estimates of teacher effectiveness in LAUSD are a biased proxy for teacher quality.”

Next, they developed an alternative, arguably stronger value-added model and compared the results to the L.A. Times model. In addition to the variables used in the Times’ approach, they controlled for (1) a longer history of a student’s test performance, (2) peer influence, and (3) school-level factors. If the L.A. Times model were perfectly accurate, there would be no difference in results between the two models. But this was not the case. For reading outcomes, the findings included the following:

• More than half (53.6%) of the teachers had a different effectiveness rating under the alternative model.

• Among those who changed effectiveness ratings, some moved only moderately, but 8.1% of those teachers identified as effective under our alternative model are identified as ineffective in the L.A. Times model, and 12.6% of those identified as ineffective under the alternative model are identified as effective by the L.A. Times model.

The math outcomes weren’t quite as troubling, but the findings included the following:

• Only 60.8% of teachers would retain the same effectiveness rating under both models.

• Among those who did change effectiveness ratings, some moved only moderately, but

1.4% of those teachers identified as effective under the alternative model are identified as ineffective in the L.A. Times model, and 2.7% would go from a rating of ineffective under the alternative model to effective under the L.A. Times model.

Accordingly, the effects estimated for LAUSD teachers can be quite sensitive to choices concerning the underlying statistical model. One reasonable model leads to very different conclusions about individual teachers than does a different reasonable model.

Briggs and Domingue then examined whether Buddin’s approach for determining teacher effect estimates reliably distinguishes between teachers assigned different value-added ratings. Once the specific value-added estimate for each teacher is bounded by a 95% confidence interval, they find that between 43% and 52% of teachers cannot be distinguished from a teacher of “average” effectiveness. Because the L.A. Times did not use this more conservative approach to distinguish teachers when rating them as “effective” or “ineffective”, it is likely that there are a significant number of false positives (teachers rated as effective who are really average), and false negatives (teachers rated as ineffective who are really average) in the Times’ rating system.

The new report also finds evidence that conflicts with Buddin’s finding that traditional teacher qualifications have no association with student outcomes. In fact, they found significant and meaningful associations between their value-added estimates of teachers’ effectiveness and their experience and educational background.

For the full research report, please visit: http://nepc.colorado.edu/publication/due-diligence.

The mission of the National Education Policy Center is to produce and disseminate high-quality, peer-reviewed research to inform education policy discussions. We are guided by the belief that the democratic governance of public education is strengthened when policies are based on sound evidence. For more information on NEPC, please visit http://nepc.colorado.edu/. The policy brief was made possible in part by the support of the Great Lakes Center for Education Research and Practice (greatlakescenter.org).



Comments:

February 11, 2011 at 1:46 PM

By: The Retired Principal (RP)

Ron Huberman

Ron Huberman, former CEO for the Chicago Public Schools has recently found employment in two Chicago-based private equity firms searching for investment and buyout opportunities in the fields of security, transportation, and EDUCATION! Do I hear, Chicago lobbyist?

February 11, 2011 at 2:37 PM

By: His insiders and team

he will be paid well for his info

at 911-CTA-CPS willprovide him much info for his new jobs.

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