定性研究
Information, industry experts, and secondary data may not be sufficient to define the research problem. Sometimes qualitative research must be undertaken to gain a qualitative understanding of the problem and its underlying factors. Qualitative research is unstructured, exploratory in nature, based on small samples, and may utilize popular qualitative techniques such as focus groups (group interviews), word association (asking respondents to indicate their first responses to stimulus words), and depth interviews (one-on-one interviews which probe the respondents' thoughts in detail). Other exploratory research techniques, such as pilot surveys with small samples of respondents, may also be undertaken.