Working Paper: NBER ID: w26480
Authors: Marianne Bitler; Sean Corcoran; Thurston Domina; Emily Penner
Abstract: Estimates of teacher “value-added” suggest teachers vary substantially in their ability to promote student learning. Prompted by this finding, many states and school districts have adopted value-added measures as indicators of teacher job performance. In this paper, we conduct a new test of the validity of value-added models. Using administrative student data from New York City, we apply commonly estimated value-added models to an outcome teachers cannot plausibly affect: student height. We find the standard deviation of teacher effects on height is nearly as large as that for math and reading achievement, raising obvious questions about validity. Subsequent analysis finds these “effects” are largely spurious variation (noise), rather than bias resulting from sorting on unobserved factors related to achievement. Given the difficulty of differentiating signal from noise in real-world teacher effect estimates, this paper serves as a cautionary tale for their use in practice.
Keywords: teacher value-added; student achievement; height; educational policy
JEL Codes: I20; J24
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Sorting of students to teachers based on unobserved factors (C78) | Teacher effects on height and achievement (I24) |
| Teacher effects on height (I24) | Spurious variation (C29) |
| Shrinkage methods (C59) | Variability in teacher effects (C21) |
| Teacher value-added on height (C29) | Teacher effectiveness (A21) |
| Teacher value-added on height (C29) | Teacher value-added on math and reading achievement (A29) |
| Teacher effects on height (I24) | Systematic variation in teacher effects (I24) |