Segmentation helps people find the “so what” in survey results. However, it also creates smaller groups, and small groups make percentages easier to misread.
Most professional guidance agrees on one core idea: when you publish results, you should disclose the sample size behind subgroup results so readers can judge how strong they are.
What does “minimum base size” mean?
A minimum base size is the smallest number of responses you allow before you treat a segment as “too small to interpret.”
Even if your dashboard shows % by default, every % comes from a real count. When the count is tiny, one or two responses can move the chart a lot.
Why teams set minimum bases
Teams set minimum bases for two reasons.
Reliability: small groups swing more, so comparisons become fragile.
Privacy: some organizations suppress very small cells to reduce disclosure risk.
Practical thresholds that stay factually correct
There is no single universal number. You can still give readers useful guidance.
A common approach is:
● Below ~30 responses: treat as high risk and avoid strong claims. (Many teams use ~30 as a rule of thumb, not a law.) National Center for Education Statistics
● 30–50: treat as directional and label clearly.
● 50–100: often stable enough for internal decisions.
● 100+: better for comparing segments and tracking changes.
The simplest line to include is this:
The smaller the segment, the more cautious you should be.
What to do when a segment drops below the minimum
Use one of these fixes:
● Merge categories that lead to the same business action.
● Rework the variable if it creates tiny groups everywhere.
Survey Automator’s UI warns the user in the UI when a segment is below the threshold. It also allows users to toggle between % and # so you can validate what the chart is based on.
FAQ
1. What is the minimum base size for survey segmentation?
There is no universal number. Many teams use around 30 responses as a practical minimum for a subgroup. Treat smaller groups as higher risk.
2. Why do small bases make segmentation unreliable?
Because a few answers can move the percentage a lot. Small groups create “jumpy” results that are easy to overread.
3. Should I hide results when the base is too small?
Not always. You can keep them visible, but add a clear warning and avoid strong comparisons or rankings.
4. When should I merge categories instead of showing every segment?
Merge when categories lead to the same decision, or when tiny segments keep creating noisy swings. Merging improves stability and clarity.
5. What’s the best way to present small bases in dashboards?
Show % for quick scanning, but let users toggle to # to validate what the % is based on. Add a “small base” warning below your threshold.
Keep Your Story Stable
Small base rules are not about hiding data. They are about keeping the story stable, so people trust the report.
👉 See it in action: Browse our PowerPoint report templates and discover how clear reporting makes results easier to share.