How to develop a customer satisfaction scale with optimal construct validity

In this article, we investigate how to construct a customer satisfaction (CS) scale which yields optimally valid measurements of the construct of interest. For this purpose we compare three alternative methodologies for scale development and construct validation. Furthermore, we discuss a satisfaction measurement application which is consistent with Messick’s (in: Linn (ed.) Educational measurement, 1989) construct validity theory. Following the deductive design for test development and construct validation, a multi-item measure for CS with a retail bank was developed. The measure was applied in survey research (N
= 1,689) within a Dutch retail bank. The items constituted a unidimensional scale, allowing the computation of scale scores. The tests of 11 hypotheses about scale-score characteristics demonstrated that the scale score represented the construct of CS well. Furthermore, the one-factor theory (e.g. Yi, in: Zeithaml (ed.) Review of marketing, 1990) of satisfaction/dissatisfaction was confirmed. An implication of this result is that satisfaction/dissatisfaction can be measured on one scale instead of two scales, one for satisfaction and one for dissatisfaction. The results demonstrate that the deductive design is an appropriate methodology for measure development and construct validation in applied psychological research. The article concludes that the multi-item measure is well-suited for CS measurement in retail banking and that customized satisfaction scales have advantages but also disadvantages compared to standardized scales.
Keywords: Construct validity, Psychological tests, Scale development, Customer satisfaction, Survey research