A psychometric evaluation of the expectations, perceptions, and difference-scores generated by the IS-adapted SERVQUAL instrument

This article describes the results of a study assessing the psychometric properties of the expectations and perceptions-of-performance instruments and the difference-score data contained within the information systems (IS)-Adapted SERVQUAL measurement paradigm. The central claim of this study is: In order for rational inferences to be made about service expectations, service performance perceptions, or the gap between them, each of the two instruments must exhibit reasonable psychometric properties in isolation before difference-scores are taken. Analysis of data from a field study (N = 401) through structural equation modeling (SEM) techniques produces empirical evidence indicating that both of the instruments exhibit low psychometric quality and yet the difference-scores exhibit ‘psychometric inflation’. That is, the quality of the difference-score data is in many ways apparently superior to the raw data from both instruments. Negative conclusions are reached as to the efficacy of either individual instrument and, thus, the full IS-Adapted SERVQUAL paradigm. Questions and prospects for further research in this important area of service quality measurement/management are presented, and a potentially rich future for IS service quality is outlined. It is strongly suggested that future IS service quality research be based on development of a new instrument, grounded in attributes endemic to IS services and developed using the best available development techniques.