In-depth interview (IDI, one-on-one) – Interview with a single individual, typically lasting from 30 to 90 minutes, depending on the subject matter and context. The purpose of in-depth interviews is to understand the underlying motivations, beliefs, attitudes and feelings of respondents on a particular subject. IDIs may be conducted in person at a research facility, the respondent’s home or workplace or a public location, or by telephone.

Dyads, triads – In-depth interviews with two or three people who often represent members of the same family or business team, who use a product or service and/or make purchase decisions together. The advantages of dyads and triads are an added layer of interaction between the respondents, which can draw out additional details, particularly when there is an existing intimate relationship and depth of shared knowledge to be tapped.

Paired interviews – Consecutive or interlocking interviews with two people who use and/or decide to purchase a product or service together, e.g., husband and wife, parent and child.