Both a value-added measure of teacher effectiveness and a series of scored observations bear a positive relationship to students’ future academic achievement, according to a study in the journal Labour Economics.
When a teacher scored well on one measure of teaching ability, he or she also tended to score well on the other measure, it finds.
“The value-added information is useful information, but it’s imperfect; the subjective complements it and makes us more certain in the overall evaluation,” said Jonah E. Rockoff, an associate professor at the Columbia graduate school of business and a research fellow at the National Bureau of Economic Research who was one of the study’s authors. “If someone is performing highly on both of these metrics, we can be more confident they’re actually truly outstanding.”
For the study, Mr. Rockoff and his co-author, Cecilia Speroni, then a senior research assistant at Teachers College, Columbia University, analyzed teacher-student data from New York City between 2003 and 2008. Using a value-added method, they looked at first-year teachers’ performance in the classroom.
Then, they analyzed two forms of subjective, observation-based evaluations for teachers hired through the city’s Teaching Fellows program and from a district mentoring program and compared all the measures to see how well they predicted teachers’ future performance. They found that both the observations and the test-score-based measures were correlated; that both types picked up effectiveness information; and that information was complementary. The findings also suggest that the two forms of information could serve as a check on one another: If a teacher scored well on one measure and not on the other, it could point to a problem in the evaluation.
The paper also underscores the importance of using observations in addition to value-added measures because they can pick up on teaching skills not captured by test scores.
