How respondents use verbal and numeric rating scales: a case for rescaling

Michael Bendixen and Yuliya Yurova

Nova Southeastern University

Introduction

Market researchers and academics researching in the social sciences are mainly concerned with measuring attitudes, beliefs, perceptions and behaviours. As such, they are largely confined to using verbal and numeric rating and ranking scales in their survey instruments. The way in which respondents use these scales and the arithmetic properties of the scales is of critical importance when selecting the appropriate methods of analysis. Most of these scales are ordinal in nature, which severely limits the methods of analysis that may legitimately be used to analyse the data collected by their use. Stevens (1946) made the following cautionary statement on ordinal scales:

In the strictest propriety the ordinary statistics involving means and standard deviations ought not to be used with these scales, for these statistics imply a knowledge of something more than the relative rank order of data. On the other hand, for this ‘illegal’ statisticizing there can be invoked a kind of pragmatic sanction: In numerous instances it leads to fruitful results. While the outlawing of this procedure would probably serve no good purpose, it is proper to point out that means and standard deviations computed on an ordinal scale are in error to the extent that successive intervals are unequal in size. (p. 679)