Focus Groups in Research: Size, Questions, Moderation, Analysis

Reviewed by Prof. Dr. Alexander Holtermann · Updated 16 October 2026 · 5 min read

A focus group is a moderated discussion with 5–8 participants on a defined topic. It reveals shared views and how opinions form through interaction.

Key takeaways

Focus groups are moderated group discussions that use interaction between participants as data: agreement, disagreement and how views develop.
Krueger and Casey recommend about 5–8 participants per group for most research topics and typically several groups per participant category.
A questioning route moves from opening and introductory questions through key questions to ending questions; 90 minutes is a common length.
Moderation is a skill: keep dominant voices in check, invite quieter ones and stay neutral.
Confidentiality is harder than in individual interviews, because participants hear each other. Address this explicitly in consent and ground rules.

What is a focus group?

A focus group is a moderated discussion with a small group of people about a specific topic. Unlike a group interview, in which the researcher asks each person in turn, a focus group deliberately uses interaction: participants react to each other, build on ideas, disagree and explain. That makes focus groups well suited to explore shared norms, language and the range of opinions in a group.

Focus groups are widely used in health research, education, marketing and evaluation. Krueger and Casey’s *Focus Groups: A Practical Guide for Applied Research* is the standard practical reference.

When are focus groups a good choice?

Compare them with individual interviews before you decide.

Good: “How do students perceive the new feedback policy?”
Less suitable: “How do students experience mental health crises?” (sensitive, individual)

	Focus groups	Individual interviews
Best for	Shared views, group norms, range of opinions, reactions to ideas	Personal experiences, biographies, sensitive topics
Data	Interaction, debate, collective meaning	Individual depth
Efficiency	Several voices per session	One voice per session
Risks	Dominant participants, conformity, limited confidentiality	Time-consuming, no group dynamics

Group size and number of groups

Krueger and Casey recommend roughly 5 to 8 participants for most non-commercial research; larger groups of up to 10–12 are common in market research but leave less time for each person. Smaller groups (mini-groups of 4–6) suit complex topics or participants with a lot to say. Recruit one or two extra people, as some will not show up.

Plan several groups per participant category, since one group may be dominated by a particular dynamic. A common recommendation is three to four groups per category, continuing until new groups add little new information. For a dissertation, two to four groups overall are often realistic; discuss this with your supervisor.

Decision	Typical choice
Participants per group	5–8 (mini-group 4–6)
Groups per category	Often 3–4, adjusted for saturation
Duration	60–120 minutes, often 90
Composition	Homogeneous on key characteristics (e.g. all first-years), varied otherwise

Developing the questioning route

Krueger and Casey describe a questioning route with five types of questions. Keep the wording conversational and open.

Question type	Purpose	Example
Opening	Everyone speaks early; easy and factual	Tell us your name and what you are studying.
Introductory	Introduce the topic	When you hear “feedback on assignments”, what comes to mind?
Transition	Move toward key questions	Think back to the last feedback you received. What was it like?
Key	Core of the study; most time (2–5 questions)	What makes feedback useful for you? What makes it useless?
Ending	Summarize, check, close	Of everything we discussed, what matters most? Did we miss anything?

Moderating a focus group

The moderator guides without dominating. Ideally, an assistant moderator takes notes on who speaks, seating, non-verbal reactions and key quotes, and handles recording.

Set ground rules at the start: no right or wrong answers, one person speaks at a time, respect different views, what is said in the room stays in the room.
Use the pause and the probe: “Can you say more about that?” “Does anyone see it differently?”
Manage dominant participants politely (“Thanks, let’s hear from others too”) and invite quiet ones by eye contact or name.
Stay neutral: avoid nodding agreement or commenting on answers.
Watch for groupthink: if consensus forms quickly, ask explicitly for other experiences.
Summarize at the end and ask whether the summary captures the discussion.

Online focus groups

Video-call focus groups are now common. They save travel and allow geographically spread participants, but group interaction is more difficult. Use smaller groups (4–6), shorter sessions (60–75 minutes), clear turn-taking rules and a co-moderator who handles technical issues and the chat. Check that your video platform and recording storage are approved by your university for research data.

Transcription and analysis

Transcribing focus groups is harder than individual interviews: overlapping speech and identifying speakers take time. The assistant moderator’s notes on speaking order help. Plan more transcription time than for an individual interview of the same length.

Analysis usually uses thematic analysis or qualitative content analysis. Remember that the unit of analysis is the group, not just individuals: note whether views were shared, contested or changed during the discussion, and avoid counting statements as if they were independent survey answers. You can code transcripts at /codieren.

Ethics and institutional requirements

You cannot guarantee that other participants keep what they hear confidential; say so honestly in the information sheet and ask everyone to respect confidentiality. Avoid highly sensitive topics, or offer individual interviews as an alternative. Ethics committees typically ask for the questioning route, consent forms and data handling plan. Requirements differ by institution; your university’s own guidelines take precedence. Upload them to Professor Digital and the plan is tailored to them.

Frequently asked questions

How many people should be in a focus group?

For most research topics about 5–8 participants (Krueger & Casey). Smaller groups of 4–6 work better online or for complex topics.

How many focus groups do I need?

Often three to four per participant category, until new groups add little new information. In dissertations, two to four groups overall are common.

What is the difference between a focus group and a group interview?

In a group interview the researcher questions individuals in turn. In a focus group, interaction between participants is the main source of data.

How long should a focus group last?

Usually 60–120 minutes, often around 90. Online focus groups work better at 60–75 minutes.

How do you analyze focus group data?

Usually with thematic analysis or qualitative content analysis, paying attention to interaction: which views were shared, contested or changed during the discussion.

Sources and further reading

Krueger, R. A., & Casey, M. A. (2015). Focus Groups: A Practical Guide for Applied Research (5th ed.). Sage.
Clark, T., Foster, L., Sloan, L., & Bryman, A. (2021). Bryman’s Social Research Methods (6th ed.). Oxford University Press.

Your university’s examination regulations and style guide always take precedence.