David Collier’s work on measurement validity and methods of validation establishes a baseline understanding that still largely describes the state of theory and practice. Scholars have developed some new ideas, and real-world conditions have changed in ways that shift the picture in subtle but important ways, but the road map that Collier’s work set up remains a useful guide to the landscape. There may well be sufficient differences between the ethnographic and interpretive measurement methods that have gained intellectual ground in recent years, in comparison with the more established case-based tradition, to potentially divide the tradition in two. The availability of large, complex data sets through digital distribution pushes scholars toward statistical techniques and, in particular, toward more generalized measurement hypotheses – a trend that leads to good research but also produces some losses. There may be opportunities for research that brings case-based techniques back in to ground these methods in more specificity, although the challenge of how to do this efficiently will demand serious methodological work. Finally, the text-as-data tradition shows scholars who have run ahead of the methodological literature in terms of mixing methods across measurement traditions and the qualitative/quantitative divide.

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. This chapter addresses this gap by exploring four themes. First, the chapter establishes a shared framework that allows quantitative and qualitative scholars to assess more effectively, and communicate about, issues of valid measurement. Second, the chapter underscores the need to draw a clear distinction between measurement issues and disputes about concepts. Third, the chapter discusses 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, the chapter addresses 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.