depth interview
noun [ C ]
MARKETING ukus(also in-depth interview)an occasion when someone is asked detailed questions, for example, about the products or services that they buy or would like to buy:
Depth interviews are a useful type of qualitative market research, and are often to be preferred to focus groups.
depth interviewing
noun [ U ] (also in-depth interviewing)
Depth interviewing often requires repeated sessions with the interviewee.