The only effective way to measure service delivery in a retail environment is to use the skills of trained mystery customers.
Mystery customer research is most effective when conducted by trained assessors who are able to report on the detail of their experiences - how customers are treated is separated from the impressions and perceptions that are inherent in other forms of measurement.

Mystery customer assessments are most effective when they are:

Independent of the commissioning company so that no internal biases can influence the findings, either in fact or in the perception of the participants.

Objective in their measurement so that the opinion of the assessor has no effect on the measurement.

Consistent in application by the use of trained assessors so that direct comparisons can be made between assessments and over time.

Accurate in completion so that the resulting reports and analyses are accepted by the participants.

Comprehensive in coverage so that the full range of service opportunities are assessed.

Communicated in the most appropriate manner to the participants and to the management team.

Repeated regularly over time so that the improvement in the performance may be measured.