Level of Measurement

Abstract

The distinctions between nominal, ordinal, interval, and ratio measurement were popularized by S. S. Stevens. Unfortunately, positions taken by Stevens have often been disseminated without criticism. One problem is the common assumption that "ordinal" statistics are the best statistics to use for presumed noninterval continuous social variables, when, in fact, they use addition, subtraction, and division, which make the measurements interval by definition. Additionally, the relationship of the normal distribution to interval measurement is commonly misunderstood, the latter existing by definition if a normal distribution exists. Concern with levels of measurements may mislead persons into attending to issues other than maximizing (utility, given) the particular limits of the state of the measurement art in the social sciences.