An in-depth interview is a qualitative research method in which just one person is interviewed, usually for 1.5 up to 2 hours.
Also known as a ‘one-on-one’, there are instances when a third individual may be present, such as a client’s technical expert, engineer, or product development person who can probe and/or clarify questions about specific subject matter.
IDIs are normally carried out face to face, but occasionally can be done over the phone. A mix can be accomplished.
A discussion guide is used to frame the conversation. Many questions are open-ended rather than yes/no or multiple choice format.
When to use IDIs?
- IDIs can provide the majority of content to pursue in focus groups, or surveys administered to a larger, more projectable sample of a population.
- While a focus group moderator can gain input from 10 people in the same amount of time required for one in-depth interview, that method involves the costs of facility rental and refreshments, plus the expense of having clients commute to, and spend time viewing the discussion. Also, compared to a 90 minute in-depth interview, a focus group member generally participates (speaks) for at most about one-tenth of the session, or fewer than 10 minutes.
- Less time is needed to schedule an IDI with one person than trying to assemble several people for a focus group.