Scales and Statistics

Over a quarter of a century has elapsed since the publication of Stevens' (1946) influential paper on the relationship between scales of measurement and appropriate statistics; nevertheless, the debate is still continuing. The central issue in the debate is the nature of the relationship between ordinal and interval scales, and parametric and nonparametric statistics. A related and equally important issue is the extent to which scales can be unerringly classified. The distinction between ordinal and interval scales is not a black-and-white distinction: many kinds of summated scales occupy a grey region somewhere in between.