Start with the question, not the format
Customer interviews help researchers understand how people describe their needs, make choices, and experience a product or service. A one-on-one interview is a conversation between a researcher and one participant. A group interview brings several participants into the same discussion, often with a moderator guiding the conversation. Both can produce useful insights, but they create different conditions for sharing them.
Before choosing a format, write down what you need to learn. Are you trying to understand a person’s decision in detail, including what happened before and after a purchase? Or do you want to hear how people respond to competing ideas and build on one another’s comments? The first question often favors individual interviews; the second may benefit from a group. Neither format tells you how common a view is across a wider audience without additional research.
Use one-on-one interviews for depth and privacy
Individual interviews give participants room to explain events in their own order. The interviewer can ask for specifics, revisit a confusing answer, and follow an unexpected but relevant topic. This makes the format useful for exploring a buying journey, observing how someone uses a service, or learning why a particular choice felt difficult.
A private conversation can also make it easier to discuss experiences people might hesitate to share in front of strangers or colleagues. That does not guarantee candor: participants may still want to present themselves positively or may struggle to recall past decisions. Ask about concrete recent examples rather than relying only on broad questions such as “What do you usually do?”
The trade-off is that each conversation captures one person’s perspective without the reactions that arise in a group. Comparing interviews requires careful notes and a consistent set of core questions. Keep space for follow-up questions, but cover the same essential topics with each participant so differences are easier to interpret.
Use group interviews to explore reactions and shared language
Group interviews are useful when the interaction itself can teach you something. Hearing one participant describe a problem may prompt another to agree, challenge an assumption, or offer a different example. A group can reveal the words people use together, the points they debate, and the ways they interpret a concept when other perspectives are present.
This can work well for exploring early ideas, comparing messages, or understanding an experience that people commonly discuss with others. It works less well when each participant needs a long, detailed turn, or when the subject is private. Groups also introduce social pressure. A confident speaker may steer the conversation, while quieter participants may hold back. Agreement in the room is not necessarily agreement outside it.
A moderator can reduce these problems by asking everyone to give an initial response before open discussion, inviting quieter people in without putting them on the spot, and asking for examples behind strong opinions. The goal is not to force consensus. Disagreement, hesitation, and changes of mind may be among the most useful observations.
Match the format to the people and setting
Consider participants’ relationships as well as your topic. People from the same workplace, household, or customer community may avoid contradicting one another, especially if there is a difference in status. Strangers may speak more freely about some topics but need more time to feel comfortable. If a participant’s perspective could be overshadowed by others, an individual interview may be the better choice.
Practical constraints matter too. A group requires people to be available at the same time and gives each person less speaking time. Individual sessions can be easier to schedule separately, though conducting many of them takes interviewer time. Remote or in-person sessions can work in either format; what matters is whether participants can hear, respond, and, when needed, show the behavior or materials you are asking about.
Interpret findings in light of the format
The two approaches can complement each other. You might begin with individual interviews to identify recurring experiences, then use a group to see how people discuss possible responses. Alternatively, a group may surface a disagreement worth exploring privately afterward. Choose the sequence because it serves the question, not because one format is inherently more thorough.
When reviewing notes, distinguish what a person volunteered from what emerged after someone else spoke. Record concrete examples alongside opinions, and look for exceptions rather than counting how many participants nodded. A useful conclusion names both the insight and its limits: what these participants helped you understand, what remains unclear, and what decision the findings can reasonably inform.
