What Can My Sample Tell Me?
Explore anticipated precision for a single proportion and recruitment allowances for missing outcomes.
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Planning illustration for one binomial proportion from independent observations. Enter the number with an observed outcome, then explore how much recruitment may be needed.
Anticipated precision
40.38% to 59.62%
Illustrative two-sided 95% Wilson interval, plugging in your expected proportion. Full width: 19.23 percentage points.
Recruitment target allowing for expected loss: 112.
Method and limits
Wilson interval evaluated at the expected proportion; actual observed intervals will vary. Recruitment = ceiling(n / (1 − loss)). Increasing recruitment does not correct missing-data bias. This is not a power calculation and does not handle clustering, finite-population sampling, repeated measures, or comparisons between groups.
NIST: Wilson interval method · Existing sample-size planning calculator