The in-depth interview (IDI), also referred to as a “depth” or “one-on-one” interview,
involves a trained interviewer asking a respondent a set of semi-structured, probing questions usually in a face-to-face setting. The typical setting for this type of interview is either
the respondent’s home or office, or some type of centralized interviewing center convenient
for the respondent.
Some research firms use hybrid in-depth interviewing techniques combining Internet and phone interviewing. In these cases, the conversation can be extended over several days giving participants more time to consider their answers.8 Use of the Internet also enables consumers to be exposed to visual and audio stimuli, thus overcoming the major limitation of in-depth interviews over the phone. Two more IDI methods have emerged in recent years: online IDIs using webcams and online text-based chat.