On the Nature of Measurement

Over time, the concept of measurement has come to be associated with precision, accuracy, objectivity, and overall trustworthiness. In this chapter we engage with the question of how educational measurement can be understood with respect to measurement more broadly, and if and how instances of educational measurement earn this claimed trustworthiness. In section 2 of the chapter, we trace some key historical developments that help to explain how the concepts and terminology of measurement came to be invoked in educational and psychological contexts. In section 3 we argue that irrespective of the field of application or disciplinary context, successful instances of measurement will always involve certain components that serve to justify its claimed trustworthiness. We introduce a TISM framework for understanding measurement with respect to four central components: Theory (T), Instrumentation (I), Scales & Units (S), and Modeling (M). We illustrate and apply the TISM framework briefly to the physical science context of measuring temperature and then more extensively to the educational context of measuring reading comprehension. Although the central components of measurement are present in each context, there are unique challenges in education. In section 4 of the chapter, we take a closer look at three of these challenges that are likely to remain areas for discussion and debate in the future: (1) the meaning of validity and how this should inform measurement practices, (2) evolving conceptualizations of measurement error and uncertainty, and (3) the role of measuring scales and units in the evaluation of magnitudes.