ClarityHow to use this tool
- Enter planning proportion, margin in percentage points, critical z value.
- Select Calculate to view the result.
- Check the method and assumptions below before using the result.
Input reference and sample values
Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.
| Input | Format and units | Sample |
|---|---|---|
| Planning proportion | Numeric value. Minimum: 0.000001. Maximum: 0.999999. | 0.5 |
| Margin in percentage points | Numeric value. Must be greater than zero. | 5 |
| Critical z value | Numeric value. Must be greater than zero. | 1.95996398 |
Result for these sample inputs
385 observations
Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.
The method, explained
n = ceil[z²p(1 − p)/(margin/100)²].
Using planning proportion = 0.5, margin in percentage points = 5, critical z value = 1.95996398454, the result is 385 observations. Change these example inputs to match your task; use the method above to check each step.
What to keep in mind
Simple random sampling approximation without finite-population adjustment or nonresponse inflation. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.
Methodology maintained by ClarityKit. How these tools are built and checked.