An empirical assessment of the extended service quality model

Abstract

The purpose of this article is to conduct an empirical assessment of the extended service quality model proposed by Zeithaml, Berry & Parasuraman. The article provides a brief review of the gap concept as a measurement framework for service quality issues. This is followed by a description of the relationships in the extended service quality model and how it can be tested. The assessment consists of three steps. First, the internal consistency and the discriminant validity of the scales used to measure the latent variables of the extended service quality model are investigated. Based on these results an amended service quality model is fitted to the data. Finally, a revised structure for a more appropriate service quality model is suggested based on a structural equation assessment of an amended service quality model. The questionnaire was mailed to a total of 10 000 customers of a large national electricity utility in the United Kingdom. The total was divided into 5 000 each for business and domestic customers, which was again subdivided into 2 500 active users and 2 500 inactive users of the company's services. After elimination of incomplete questionnaires, a total of 1 860 questionnaires were used in the analysis, an effective response rate of 18.6%. The empirical results reported in this study suggest that considerable research is still required to enhance our understanding of the factors influencing service quality. Three concerns are the improvement of the psychometric capabilities of the scales used in this study, the search for unspecified constructs and antecedents which may influence individual gaps, and the unbundling of the internal gaps.