Chosing interview methodologies

Caretaker: Kayleigh

 What are they and choosing the right one (pros and cons)?

  • Focus groups:  6 – 8 participants, unknown to each other, brought together with an impartial moderator in a neutral location (like a hotel or viewing facility)

  • Mini groups: 4 or 5 participants, brought together with an impartial moderator in a neutral location (like a hotel or viewing facility), but can be comprised of a couple of friendship pairs

  • Triads: 3 respondents that typically already know each other

  • Dyads/Paired Depths: 2 respondents that typically know each other already (“friendship pairs”)

  • IDI (individual depth interviews): an in-depth market research interview with a trained executive interviewer and one respondent – often just called a depth.

Focus groups

Good for:

  • Understanding in participants own terms and language 
  • Quick way to get direction; cover a large sample size quickly, consensus emerges within the group, and only need a few groups
  • Benefit from the interaction between the different personalities
  • Iterative insight development; greater richness of data
  • Being in a group encourages participants to share feelings or opinions they might not have thought of in an individual interview
  • Positive brand impact (if ran well)
  • Easy to embed clients; expedites buy-in, improves efficiency.

Bad for:

  • Results may not fully represent opinion of larger target population
  • Observer bias possible
  • “Validity” of data highly dependent on skill of moderator
  • Can be hard to defend to audiences more accustomed to the large sample size of quantitative research
  • Can’t cover as much or get as deep on topics as with other methods
  • An over recruited full house can cause issues
  • Scheduling is limited; typically “after hours” only
  • Easy for people to hide or agree with consensus.

Mini groups

Bad for: 

Good for:

  • Can be nearly as expensive as full focus groups as direct costs like venue hire remain the same regardless of group size (as a rule of thumb a mini group only saves you about 30%).











  • Like paired depths & triads, a great balance of depth & consensus
  • Good for longitudinal research; smaller numbers to try and reconvene each time
  • Allows for ongoing fine tuning and iteration (because typically conduct a larger number of mini groups than focus groups, so have more opportunities for development between groups)
  • Over recruiting doesn’t present the same problems as in focus groupss (if all turn up you can still run the group effectively without harming dynamics or making snap judgments)
  • Shorter length means can schedule more in an evening or use “non traditional” timings such as Saturdays etc. because less time commitment required by the participant
  • Harder for participants to hold back / hide in a smaller group. 

Depths and triads

Bad for: 

Good for:

  • Naturally consensual: friends are often by definition similar, so can be limited different viewpoints within pairs (but when there are differences friendship makes it easier to discuss and defend these within the group vs. strangers)
  • Time consuming to conduct and analyse.
  • Effective balance between depth and consensus
  • Some interaction between participants to spark discussion and draw out latent insight
  • Friendship circumnavigates social fear; less time spent building rapport and confidence in group
  • Can explore using “non traditional” timings such as daytimes or weekends
  • Impossible for participants to hold back / hide.


Bad for: 

Good for:

  • Time consuming; take longer to execute (vs. focus groups for example which tick off a larger sample faster)
  • Repetitive: same questions over and over vs. focus groups which allow you to gain consensus on key points quickly
  • A lot of data to wade through and analyse.







  • The most in-depth methodology; can really probe and challenge extensively
  • Provides a great opportunity to explore decisions and objectively compare differences and similarities among reference group members (because it's done in analysis rather than within the research)
  • Allows for detailed exploration of a single respondent’s reactions without contamination; no group influence factors
  • Particularly valuable when researchers want individual reactions placed directly in the context of the individual’s experiences
  • Easier to conduct; less to control / be aware of that could influence or taint the results.