Does Value-Added Work Better in Elementary than Secondary Grades?

carnegieknowledgenetworkValue-added methodology is being applied to the evaluation of teachers in tested grades and subjects, but the vast majority of the research on value-added measures focuses on elementary schools only. Secondary grades differ from elementary grades in ways that are meaningful for the validity and reliability of value-added measures for secondary teachers.

In a new report, “Does Value Added Work Better in Elementary than Secondary Grades?”, Carnegie Panelist Doug Harris, Associate Professor of Economics and University Endowed Chair in Public Education at Tulane University, addresses the question, how do differences between elementary and secondary schools affect the validity and reliability of value-added for teacher evaluation?

Following is the introduction to the report:

There is a growing body of research on the validity and reliability of value-added measures, but most of this research has focused on elementary grades. This is because, in some respects, elementary grades represent the “best-case” scenario for using value-added. Value-added measures require annual testing and, in most states, students are tested every year in elementary and middle school (grades 3-8), but in only one year in high school. Also, a large share of elementary students spend almost all their instructional time with one teacher, so it is easier to attribute learning in math and reading to that teacher.[1]

Driven by several federal initiatives such as Race to the Top, Teacher Incentive Fund, and ESEA waivers, however, many states have incorporated value-added measures into the evaluations not only of elementary teachers but of middle and high school teachers as well. Almost all states have committed to one of the two Common Core assessments that will test annually in high school, and there is little doubt that value-added will be expanded to the grades in which the new assessments are introduced.[2] In order to assess value-added and the validity and reliability of value-added measures, it is important to consider the significant differences across grades in the ways teachers’ work and students’ time are organized.

As we describe below, the evidence shows that there are differences in the validity of value-added measures across grades for two primary reasons.  First, middle and high schools “track” students; that is, students are assigned to courses based on prior academic performance or other student characteristics. Tracking not only changes our ability to account for differences in the students who teachers educate, but also the degree to which the curriculum aligns with the tests. Second, the structure of schooling and testing vary considerably by grade level in ways that affect reliability in sometimes unexpected ways. The problems are partly correctable, but, as we show, more research is necessary to understand how problematic existing measures are and how they might be improved.

In conclusion, the fact that secondary students are often placed in different tracks or groupings based on various factors such as students’ previous academic records means that the way value-added evaluations function is different than is the case for primary students, who are usually grouped heterogeneously.  This, combined with the fact that primary students often take standardized state tests that can be used to show year over year gains means that value-added is generally stronger for primary than secondary, where sequential courses sometimes have little overlapping content. However, other factors at the secondary level such as higher number of students and growing prevalence of standardized tests for secondary students could strengthen the value-added measure at the secondary level.

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