F4. Recruiting Interview and Survey Participants Without the Bias
After this lesson you can
- Choose a purposeful sampling strategy that matches each validation question
- Write a short screener based on recent behavior, with a fit rule set in advance
- Avoid friends-and-family, convenience and power-imbalance bias
- Handle incentives so they thank people without distorting answers
- Read saturation numbers as contested guides rather than stopping rules
Video coming soon
Videos are planned to publish from December 2026.
A practical lesson on recruiting the right people for interviews and surveys, so that answers reflect a segment rather than a founder's friends. It covers purposeful and criterion sampling, screeners, power imbalances, incentives, and the evidence and debate on how many interviews to plan.
Questions and answers
Questions a learner would ask about this lesson. Think through your own answer before you open each one.
- Why not just interview friends and classmates?
Show answer
Friends are usually honest people, but they are the most likely to be polite, and they know what you hope to hear. In the lesson, Founder B's first five "customer interviews" were all department friends, and all five said the idea sounded great. Purposeful recruiting uses written criteria, several channels per segment, and strangers who owe you nothing.
- What is purposeful sampling?
Show answer
Palinkas and colleagues (2015) describe it as selecting information-rich cases related to the question you are studying. A common form is criterion sampling, which selects people who meet a stated criterion, such as having faced the problem in the last year or approving this kind of spending.
- How many interviews should I plan?
Show answer
The saturation studies offer a starting range for homogeneous groups, which the course plans as about 12 to 30 per distinct segment. Guest and colleagues (2006) found saturation within 12 interviews, Hennink and colleagues (2017) found code saturation at 9 and meaning saturation at 16 to 24, and Griffin and Hauser (1993) stated 20 to 30 interviews as a hypothesis. These numbers are guides from specific studies, not a stopping rule, and Braun and Clarke (2021) argue saturation is not a coherent sample-size rationale for reflexive thematic analysis.
- What makes a good screener question?
Show answer
A screener is three to five short questions that confirm a person fits your segment. Strong questions ask about recent behavior, such as "In the last two years, did you commission an evaluation?", rather than opinions or intentions like "Would you hire a consultant?" Write the fit rule before you recruit so you cannot loosen it later.
- Why does the lesson say never to recruit people who depend on you?
Show answer
When someone depends on you, such as students you grade or lab members you supervise, their willingness may not be a free choice. The lesson calls this a power imbalance, using one national ethics policy's term "undue influence," and notes that advisor or lab relationships can also raise conflicts. Recruit through channels outside your authority.
Practice quiz
- Question 1Purposeful sampling, as reviewed by Palinkas and colleagues, selects what?
- Question 2Which screener question is strongest?
- Question 3Founder D wants feedback from lab members they supervise. What is the main problem?
- Question 4What does Braun and Clarke's 2021 paper argue about saturation?
- Question 5In Hennink and colleagues' 2017 study of 25 interviews, when was code saturation reached?
- Question 6A founder runs 40 interviews, all recruited through their own group chats. What does the lesson say about this?
- Question 7Which incentive fits the lesson's description of a modest thank-you?
- Question 8Founder B planned about how many interviews per segment, and how did they treat that number?
- Question 9In Founder B's rebuilt plan, what new job did their department friends get?
- Question 10Why does the lesson suggest tracking who declined at each stage and channel?
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