Free tool · runs in your browser
How sure is your visibility rate?
A rate measured on a handful of prompts has a wide range of true values behind it. Enter your counts to see that range, and how many prompts a narrower one would take. Nothing you type leaves this page.
Your rate
Rate
20.0%
4 of 20 answers
95% interval
8.1% – 41.6%
±16.8 points · 33.5 points wide
This interval is wider than a third of the scale, so it cannot say which third of the range the rate is in. More prompts narrow it fastest.
Prompts needed for a margin
The smallest number of prompts, one answer each, whose 95% interval is no wider than the margin. 50% is the worst case: plan on that column if you do not know your rate yet.
| Margin | At 50% (worst case) | At your rate (20.0%) |
|---|---|---|
| ±5 points | 381 | 245 |
| ±10 points | 93 | 60 |
| ±15 points | 39 | 26 |
| ±20 points | 21 | 14 |
With your 20 prompts run once, the margin at this rate is ±16.8 points.
Method: Wilson score interval, 95%, without continuity correction, the same one the Promvia dashboard prints. ±X points is half the interval's width. The interval covers sampling noise only: it cannot correct a prompt set that leans toward questions you already do well on.