In Depth Interviews
In depth Interviews or IDI’s follow a very similar format to Focus Groups and Triads, except that this is a discussion with one respondent only. The main purpose of conducting an in-depth interview as opposed to a focus group is to avoid “group think,” which refers to the notion of respondents influencing each other’s views.
Telephone Depth Interviews
Telephone depth interviews or TDI’s follow the exact pattern of an in-depth interview. It is a one-on-one discussion between a respondent and an interviewer, conducted over the phone instead of in-person.