Does the precision and stability of value-added estimates of teacher performance depend on the types of students they serve?

In this paper, we investigate how the precision and year-to-year stability of a teacher’s value-added estimate relate to student characteristics. We find that teachers serving initially higher performing students have more precise value-added estimates and in most cases have higher year-to-year stability levels than teachers with lower performing students. We also decompose the variation in value-added estimates into components that reflect persistent and transitory variation in true teacher performance as well as variation caused by imprecision in the estimates. We find that teachers with lower performing students have less precision in their estimates and more transitory variation in value-added from year to year than other teachers. Our estimates imply that if teachers serving initially lower performing students had levels of precision and transitory variation in their value-added estimates equal to those serving higher performing students, the year-to-year stability in their estimates would actually exceed that of teachers with initially higher performing students. [ABSTRACT FROM AUTHOR]