Like the open-ended questions on questionnaires, interviews tend to yield very rich qualitative data. Although the interviewer generally uses a structured format of prepared questions, many of them are open-ended; the interviewer will thus hear broad opinions and perceptions and can then probe for concrete examples and clarify answers that could be interpreted more than one way. At the same time, more specific questions are used to elicit information about particular areas of behavior. Once all the responses are collected, the interviewer analyzes them to extract themes, patterns, and key messages and prepares a report of the findings. The report may also include recommendations for improvement.

While the two methods of data collection differ in their form and the type of information they produce, they are far from being mutually exclusive. Used in combination, they can create a picture of an individual’s behavior and its impact on others that neither method could produce on its own.