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Scholars routinely make claims that presuppose the validity of the observations and measurements that operationalize their concepts. Yet, despite recent advances in political science methods, surprisingly little attention has been devoted to measurement validity. We address this gap by exploring four themes.
First, we seek to establish a shared framework that allows quantitative and qualitative scholars to assess more effectively, and communicate about, issues of valid measurement. Second, we underscore the need to draw a clear distinction between measurement issues and disputes about concepts. Third, we discuss the contextual specificity of measurement claims, exploring a variety of measurement strategies that seek to combine generality and validity by devoting greater attention to context. Fourth, we address the proliferation of terms for alternative measurement validation procedures and offer an account of the three main types of validation most relevant to political scientists.
Researchers routinely make complex choices about linking concepts to observations, that is, about connecting ideas with facts. These choices raise the basic question of measurement validity: Do the observations meaningfully capture the ideas contained in the concepts? We will explore the meaning of this question as well as procedures for answering it. In the process we seek to formulate a methodological standard that can be applied in both qualitative and quantitative research.
Measurement validity is specifically concerned with whether operationalization and the scoring of cases adequately reflect the concept the researcher seeks to measure. This is one aspect of the broader set of analytic tasks that King, Keohane, and Verba (1994, chap. 2) call "descriptive inference," which also encompasses, for example, inferences from samples to populations. Measurement validity is distinct from the validity of "causal inference" (chap. 3), which Cook and Campbell (1979) further differentiate into internal and external validity.' Although measurement validity is interconnected with causal inference, it stands as an important methodological topic in its own right.
New attention to measurement validity is overdue in political science. While there has been an ongoing concern with applying various tools of measurement validation (Berry et al. 1998; Bollen 1993; Elkins 2000; Hill, Hanna, and Shafqat 1997; Schrodt and Gerner 1994), no major statement on this topic has appeared since Zeller and Carmines (1980) and Bollen (1989). Although King, Keohane, and Verba (1994, 25,...