Many researchers have struggled with the issue of how to measure service quality.  Perhaps the most widely used measure is based on a set of five dimensions which have been consistently ranked by customers to be most important for service quality, regardless of service industry. These dimensions defined by the SERVQUAL measurement instrument are as follows:

Tangibles: appearance of physical facilities, equipment, personnel, and communication materials;

Reliability:
ability to perform the promised service dependably and accurately;

Responsiveness: willingness to help customers and provide prompt service;

Assurance: knowledge and courtesy of employees and their ability to convey trust and confidence; and

Empathy: the caring, individualized attention the firm provides its customers.

These five SERVQUAL dimensions are used to measure the gap between customers’ expectation for excellence and their perception of actual service delivered. The SERVQUAL instrument, when applied over time, helps service providers understand both customer expectations, perceptions of specific services, and areas of needed quality improvements.

SERVQUAL has been used in many ways, such as identifying specific service elements requiring improvement, and targeting training opportunities for service staff.

Proper development of items used in the SERVQUAL instrument provides rich item-level information that leads to practical implications for a service manager.

The service quality dimensions evaluated by SERVQUAL should be adjusted for optimal performance in different industry, public and private sector applications.

SERVQUAL scores are highly reliable, but when used in different industries may fail to produce a clear delineation of the five basic dimensions.Other measures, such as the Six Sigma model should be considered for applicability in quantifying the gap between service expectations and perceptions.