Interviews that sacrifice uniformity in questioning to achieve fuller development of information are qualitative interviews.
As we depart from the survey approach in the direction of tailoring our interviewing to each respondent, we gain in the coherence, depth and density of the material each respodent provides.
In the qualitative interview, the respondent provides information while the interviewer, as a representative of the study, is responsible for directing the respondent to the topics that matter to the study.
The interviewer at no point should engage the respondent in the small exchanges of ordinary conversation by, for example, matching one of the respondent’s observations with an observation of his or her own.
The fuller responses obtained by the qualitative study cannot be easily categorized, and their analysis will rely less on counting and correlating and more on interpretation, summary, and integration.
Source: Robert S. Weiss (1994) Learning from Strangers: The Art and Method of Qualitative Interview Studies