Monday, November 10, 2014

Validating Teacher Effect Estimates

In a widely cited study, Chetty, Friedman, and Rockoff CFR) evaluated the degree of bias in teacher value-added estimates using a research design with data from New York City.  They concluded that there is little to no bias in their estimates.  Using the same model with data from North Carolina, Rothstein (2014) argued that the CFR research design is invalid, given a relationship between student baseline test scores and teachers' value-added.

In this paper, researchers replicated the CFR analysis using data from the Los Angeles Unified School District and similarly found that teacher value-added estimates were valid predictors of student achievement.  They also demonstrate that Rothstein's test does not invalidate the CFR design and instead reflects a mechanical relationship, given that teacher value-added scores from prior years and baseline test scores can be based on the same data.  

In addition, the paer explores the (1) predictive validity of value-added estimates drawn from the same, similar, and different schools, (2) an alternative way of estimating differences in access to effective teaching by taking teacher experience into account, and (3) the implications of alternative ways of imputing value-added when it cannot be estimated directly.  

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