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Reliability and Validity of Inferences About Teachers Based On Student Test Scores

Author(s):
Haertel, Edward H.
Publication Year:
2013
Source:
William H. Angoff Memorial Lecture Series
Document Type:
Publication
Page Count:
28
Subject/Key Words:
Angoff Memorial Lecture Series Generalizability Reliability Teacher Effectiveness Teacher Evaluation Validity Value Added Models (VAM)

Abstract

The 14th William H. Angoff Memorial Lecture was presented at the National Press Club, Washington, D.C., on March 22, 2013 Policymakers and school administrators have embraced value-added models of teacher effectiveness as tools for educational improvement. Teacher value-added estimates may be viewed as complicated scores of a certain kind. This suggests using a test validation model to examine their reliability and validity. Validation begins with an interpretive argument for inferences or actions based on value-added scores. That argument addresses (a) the meaning of the scores themselves — whether they measure the intended construct; (b) their generalizability — whether the results are stable from year to year or using different student tests, for example; and (c) the relation of value-added scores to broader notions of teacher effectiveness — whether teachers’ effectiveness in raising test scores can serve as a proxy for other aspects of teaching quality. Next, the interpretive argument directs attention to rationales for the expected benefits of particular value-added score uses or interpretations, as well as plausible unintended consequences. This kind of systematic analysis raises serious questions about some popular policy prescriptions based on teacher value-added scores.

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