Quantitative studies allow a firm to develop an understanding of the "big picture" of their customers' experiences based upon a relatively small number of interviews.
In most cases, the results of quantitative studies are based upon the responses of a relatively large number of interviews.
Depending upon the size of the population and the amount of segmentation desired, "large" can be as few as 50 responses or range from several hundred to thousands of interviews.
Mail-based, telephone-based, and (more recently) Internet-based surveys and related customer data collection.
Qualitative studies are used by firms to provide a more detailed and/or unconstrained understanding of customer experiences.