Focus group or in-depth interview: which one fits your decision
Choose a focus group when you need to see how people discuss, persuade each other and react together to a brand or a stimulus. Choose an in-depth interview when the topic is personal, the profile is scarce or you need the full story of a single decision. Often the right answer is to combine both.
What is the difference between a focus group and an in-depth interview?
A focus group is a guided conversation with a group of people who share a defined profile. At WAV we work with groups of 6 to 8 people and sessions of 90 to 120 minutes. What it produces is interaction: how one person answers another, which argument wins, which objection only comes up once someone dares to say it.
An in-depth interview is a conversation between one person and an interviewer. There is no group to sway or to spark ideas. What it produces is depth: the complete sequence of a purchase, the reasons someone would not share in front of strangers, the personal context behind a choice.
Neither is better in general. They are tools for different questions, and the question that matters is what your decision needs.
When does a focus group fit?
- When contrast is part of the finding. Watching customers and non-customers defend their reasons, in separate groups, shows what weighs for each and in which words.
- When there is something to show or try. A concept, a pack, an ad, a product. The group's reaction, and what shifts after hearing others, says a lot.
- When you need the consumer's own language. Groups surface the expressions people actually use, useful for a campaign or for writing a survey.
- When the topic is easy to discuss in public. Brands, consumer categories, the buying experience, service.
When does an in-depth interview fit?
- When the topic is sensitive. Health, personal finances, family conflict: in front of a group, many people hold back what matters.
- When the profile is scarce or hard to gather. Executives, specialists or buyers of something rare, who will not be in one room at the same hour.
- When you need to rebuild a long process. A purchase that took months and involved several people is easier to understand told from start to finish by one voice.
- When group pressure distorts answers. If the topic invites the socially correct reply, talking one to one reduces that effect.
Quick comparison
| Criterion | Focus group | In-depth interview |
|---|---|---|
| What it produces | Interaction, contrast and shared language | Depth, personal history and private motives |
| People per session | 6 to 8 in WAV's practice | One |
| Stimuli | Ideal for showing and trying things in a group | Possible, without others' reactions |
| Sensitive topics | Can inhibit | More comfortable |
| Influence between participants | Present; managed with the guide and with written opinions before discussion | None |
| Scarce profiles | Hard to bring together | Scheduled one person at a time |
How do you keep the group from steering the answers?
The most common criticism of focus groups is that one dominant person sways everyone else. The risk is real, and the fix is in the design. At WAV we use the nominal group technique: before each topic is discussed, every participant writes down their own view. That records what each person thought before hearing the others, and the moderator can invite whoever wrote something different to speak. The discussion guide sets aside time for that individual moment in each block.
Can you combine them?
Yes, and it is often the most useful option. Two common combinations:
- Interviews first, groups after. Interviews uncover the topics and the words; groups test them and show which ones hold up when others weigh in.
- Groups first, interviews after. Groups show the landscape; interviews go deeper into a profile that turned out to be key, or into a topic nobody wanted to raise in front of others.
What changes in the analysis?
In an interview there is no question about who is speaking. In a group there is, and it is harder than it looks: with a single microphone for the whole room, every sentence has to be attributed afterwards, and mistakes move findings from one segment to another without anyone noticing. That is why at WAV every participant wears their own microphone and the room is recorded in 360. We explain it in how to know who said what in a focus group.
The rule is the same for both methods: every finding comes with its literal quote, the profile of who said it and the exact moment in the recording. You can see how that looks in the sample report, built from a fictional study.