Reference table
How many user interviews by research type
Recommended sample sizes for seven kinds of qualitative study
A reference table of how many user interviews to plan for seven common research types: usability testing, exploratory discovery, problem validation, multiple segments, Jobs to Be Done switch interviews, voice of customer programs and employee listening studies. Each row gives a recommended range and the main factor that moves it. Use it to scope a study before you recruit, then adjust as saturation shows up in your coding.
Where this appears
What's in this reference table
| Research type | Recommended range | Key consideration |
|---|---|---|
| Usability testing | 5 to 8 per segment | Nielsen Norman's 85% issue capture principle |
| Exploratory discovery | 8 to 12 | Homogeneous B2B or B2C audiences |
| Problem validation | 10 to 15 | Known hypotheses tested against defined segments |
| Multiple user segments | 6 to 8 per segment | Each segment is its own mini-study |
| Jobs to Be Done switch interviews | 12 to 20 | Need diversity across timeline moments |
| Voice of customer programs | Ongoing batches of 5 to 10 | Continuous model; saturation resets with new contexts |
| Employee listening studies | 15 to 25 | Organizational complexity and hierarchy need more |
Use this image
Free to use in your docs, decks and posts under CC BY 4.0, as long as you credit Koji with a link to this page. To embed it, paste this into your page:
html
<a href="https://www.koji.so/visuals/user-interview-sample-size-by-research-type"><img src="https://www.koji.so/visuals/user-interview-sample-size-by-research-type/user-interview-sample-size-by-research-type.png" alt="Table of recommended user interview counts for seven research types, from usability testing at 5 to 8 per segment to employee listening studies at 15 to 25." width="1200" height="878" /></a>
<p>Source: <a href="https://www.koji.so/visuals/user-interview-sample-size-by-research-type">How many user interviews by research type</a>, Koji</p>
