Working Paper: NBER ID: w14065
Authors: Brian A. Jacob; Lars Lefgren; David Sims
Abstract: Educational interventions are often narrowly targeted and temporary, and evaluations often focus on the short-run impacts of the intervention. Insofar as the positive effects of educational interventions fadeout over time, however, such assessments may be misleading. In this paper, we develop a simple statistical framework to empirically assess the persistence of treatment effects in education. To begin, we present a simple model of student learning that incorporates permanent as well as transitory learning gains. Using this model, we demonstrate how the parameter of interest - the persistence of a particular measurable education input - can be recovered via instrumental variables as a particular local average treatment effect. We initially motivate this strategy in the context of teacher quality, but then generalize the model to consider educational interventions more generally. Using administrative data that links students and teachers, we construct measures of teacher effectiveness and then estimate the persistence of these teacher value-added measures on student test scores. We find that teacher-induced gains in math and reading achievement quickly erode. In most cases, our point estimates suggest a one-year persistence of about one-fifth and rule out a one-year persistence rate higher than one-third.
Keywords: teacher quality; persistence; learning gains; educational interventions; value-added measures
JEL Codes: I20; I21; J20; J24; J38
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| teacher quality (A21) | student achievement (I24) |
| teacher-induced gains in math and reading achievement (A21) | deterioration of gains (F62) |
| fadeout of teacher effectiveness (I21) | depreciation of teacher influence (I21) |
| teacher quality (A21) | persistence of teacher effects (A21) |
| test scores as proxies for true knowledge (C12) | apparent fadeout of teacher effects (I21) |
| structural elements of the educational system (H52) | apparent fadeout of teacher effects (I21) |