Ironically, while quality assurance is of utmost important in services, it is utmost difficult to assure quality here. Even measuring quality is difficult in services. In the first place, quality characteristics in respect of a service are more difficult to define. Second, quality here includes many subjective elements.
We can state that service quality is ensured when the service does what the customer expects of it. This means that quality assurance in services calls for : (i) a device for understanding customer expectations of quality in the service, (ii) a mechanism for ensuring that the service is performed matching customer expectations, and (iii) a device for measuring the service quality perceived by the customer as the service goes along and on completion of the service.
Since quality assurance in services becomes difficult mainly because of the difficulty in measuring service quality, the later becomes the crux in managing service quality.