ABSTRACT
There are two approaches to the classification of scales of measurement. Psychologists tend to describe four scales: nominal, ordinal, interval and ratio. Each provides a certain level of information, with nominal providing the least and ratio the most. For the purposes of the statistical techniques described in this book, interval and ratio scales of measurement can be treated as the same. Statisticians prefer to talk of continuous, discrete and dichotomous scales. Both classificatory systems need to be considered. A further consideration which determines how a measure should be classified is what it is being used to indicate. The scale of a measure has an effect on the type of statistics which can be employed on that measure.
