Maximum versus meaningful discrimination in scale response: Implications for validity of measurement of consumer perceptions about products

This paper argues for the use of the number of response categories that are meaningful to respondents as a criterion in designing attribute rating scales in marketing in contrast to a focus in past research on using scales to maximize the discrimination elicited from respondents. Whereas scales eliciting a maximum level of discrimination may be more reliable than scales eliciting a meaningful level of discrimination, the latter are argued to be more valid in measuring sameness and difference between brands that are meaningful to respondents. Specifically, a distinction is drawn in this paper between the maximum number of categories that consumers can discriminate between and the number of categories that are meaningful to them. The meaningful number of categories refers to the number of categories that individuals typically use in thinking about an attribute in such situations as making a choice or judgment. Thus, the unique perspective of consumer behavior with its central focus on phenomena such as product judgment and choice is incorporated into the measurement of consumers' perceptions about attributes. Several studies were conducted to test hypotheses generated on the basis of the notion of the meaningful number of categories. The first study used an open-ended method (i.e., a sorting task) to measure the number of categories that are meaningful to consumers for specific attributes. Using the results of the first study as a basis, two studies demonstrated the effect of the meaningful number of categories for an attribute on scale response such that fewer scale points were used to rate products on attributes with fewer meaningful numbers of categories. Another study showed that a scale with the meaningful number of categories might be more accurate than other scales in predicting sameness and difference between brands that are meaningful to consumers. The significance of using scales with a meaningful number of categories is in validly measuring differences between products that are meaningful to consumers. (C) 2003 Elsevier Science Inc. All rights reserved.