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Quality standards and control charts applied to customer surveys
This chapter presents an application of methods and standards used in quality management and quality control to the analysis of customer satisfaction surveys. It covers, in detail, the ISO 10004 standard on guidelines for monitoring and measuring customer satisfaction, and other ISO quality standards with relevance to customer satisfaction surveys. Control charts are then introduced and described with the corresponding ISO 7870 guidelines. It discusses how standard control charts (p, c, and u charts) can be used to monitor, over time, the number or proportion of satisfied or unsatisfied customers. Additional sections describe some non-standard analysis for handling items with different importance levels, customer responses as multivariate ordinal variables, respondent patterns, prior information in a Bayesian approach, and dependence structures, when longitudinal panel data is available. Next, it presents an application of the M-test for testing how well the response sample represents the full customer population. The M-test is particularly effective in customer satisfaction surveys conducted over the internet. In such surveys, emails are typically sent to all customers so that these are, in fact, an attempted census with non-response effects. Applying the M-test assesses the representativeness of the responses and helps determine if the analysis requires weighting ...
