Statisticians' Group Issues Statement on Use of 'Value Added' Data for Teachers
If you've been following this blog, then you know that there are few more controversial policy shifts of late than the integration of "value added" methodolgies, which are based on students' standardized-test scores, into teachers' performance evaluations.
Some scholars believe that they models are too "noisy" and error-prone to be used for such purposes. Other researchers are have argued that they're akin to other widely accepted statistical estimates of performance, such as a baseball player's batting average. Still others think they could be used informally, as a "check" or screen on evaluation results rather than as a component.
There are qualitiative objections, as well, on the grounds that doubling-down on test scores could affect teaching in unproductive ways, i.e., by promoting "teaching to the test."
Adding its perspective to this volatile mix, the American Statistical Association today issued aposition statement on the use of value-added models, or VAMs. Its takeaways for the K-12 community: Proceed carefully and make sure teachers, adminsitrators, and parents are aware of VAM's limitations.
For instance, the group notes, test quality and the types of controls used in the formulas will affect the end results. Moreover, the ASA says, the focus on individual teachers' performance could detract from needed attention to system improvement.
"VAMs should be viewed within the context of quality improvement, which distinguishes aspects of quality that can be attributed to the system from those that can be attributed to individual teachers