A Measurement Is a Choice and Stevens’ Scales of Measurement Do Not Help Make It: A Response to Chalmers

Chalmers recently published a critique of the use of ordinal [Formula: see text] proposed in Zumbo et al. as a measure of test reliability in certain research settings. In this response, we take up the task of refuting Chalmers’ critique. We identify three broad misconceptions that characterize Chalmers’ criticisms: (1) confusing assumptions with consequences of mathematical models, and confusing both with definitions, (2) confusion about the definitions and relevance of Stevens’ scales of measurement, and (3) a failure to recognize that a measurement for a true quantity is a choice, not an absolute. On dissection of these misconceptions, we argue that Chalmers’ critique of ordinal [Formula: see text] is unfounded.