Reference table
Survey sample size by use case
A reference table of practical survey sample sizes for eleven common research jobs, from a quick concept read to conjoint analysis, with the reason each needs that many responses. Use it to sanity-check a plan before you field a survey, and remember that every segment you compare needs its own sample. In Koji you can set quotas per segment so each group reaches its target.
Where this appears
What's in this reference table
| Use case | Practical sample size | Why |
|---|---|---|
| Concept validation (single concept) | 50 to 150 | Directional read on appeal, fast turnaround |
| Concept testing (multiple variants) | 100 per variant | A/B level comparison |
| Pricing research (e.g. Van Westendorp) | 300 to 500 | Need range estimates, not just a point |
| NPS measurement (single market) | 300 to 400 | Confidence interval on the score |
| NPS comparison across segments | 300 per segment | Each segment needs its own n |
| Brand tracking wave | 300 to 500 per wave | Detect quarter-over-quarter movement |
| Customer satisfaction (CSAT) | 384+ | Standard 5% precision |
| Persona research | 50 to 100 per persona | Plus 15 to 30 qualitative interviews |
| Internal employee survey | Census preferred | Just ask everyone if you can |
| Pre/post product launch | 300 each wave | Power to detect a 5-point lift |
| Conjoint analysis | 300 to 500 | Need enough choice tasks |
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<a href="https://www.koji.so/visuals/survey-sample-size-by-use-case-table"><img src="https://www.koji.so/visuals/survey-sample-size-by-use-case-table/survey-sample-size-by-use-case-table.png" alt="Table of practical survey sample sizes for 11 use cases, from 50 to 150 for one concept to 300 to 500 for pricing and conjoint studies." width="1200" height="1019" /></a>
<p>Source: <a href="https://www.koji.so/visuals/survey-sample-size-by-use-case-table">Survey sample size by use case</a>, Koji</p>
