A Comparative Assessment of The Predictive Power and Diagnostic Ability of The Servqual and Servperf Scales in The Higher Education Context of Tanzania

The debate over which instrument is a better measure of service quality, between the disconfirmation-based SERVQUAL scale and the performance-based SERVPERF scale, is not over yet. While a number of studies have attempted to compare the two scales, and have concluded that the SERVPERF is a better measure of service quality, these studies have mostly focused on psychometric properties of the two alternative scales. The comparison of predictive power and the diagnostic ability of the two scales have not received adequate attention. Since the ideal service quality measuring instrument is one that is not only psychometrically sound, but is also diagnostically robust enough to identify specific service quality flaws for improvement, this study assesses and compares predictive power and diagnostic ability of the two scales in the higher education context of Tanzania. Based on the sample of 500 university students, the study concludes that, the SERVPERF scale is a superior scale in terms predictive power, while the SERVQUAL scale is superior in terms of diagnostic ability. It is recommended that, when the interest is only to assess the overall service quality, the SERVPERF scale should be preferred. On the other hand, when the interest is to identify service quality shortfalls for improvement, the SERVQUAL scale should be employed.