Example: Cell A versus Cell B leak-test passes
Independent leak-test samples: Cell A passed 470 of 500 pouches; Cell B passed 486 of 510.
Download the study reference (CSV)This is the same example used in Help. The CSV is a reference for the supplied study. Enter the checked summaries manually on Inputs; importing the CSV does not populate this calculator. Use Open example in a practice copy in Help to prefill the inputs.
1. Create the workspace
In the sidebar, open Basic Statistics and choose Confidence Intervals. Create an analysis, name it, select New blank worksheet, then choose Create analysis.
2. Choose the interval
On Inputs, choose Difference between proportions for Parameter. Enter 0.95 in Confidence level (0–1) for a 95% interval.
3. Enter the summaries
Under Summarized data, enter the following values. No worksheet columns are assigned.
Enter 500 in Number of trials (n₁).
Enter 470 in Number of events (x₁).
Enter 510 in Number of trials (n₂).
Enter 486 in Number of events (x₂).
Leave Sample proportion (p̂₁) and Sample proportion (p̂₂) blank. The entered event counts determine the proportions.
4. Run analysis
Choose Run analysis, then open Results.
5. Interpret results
Identify what the interval estimates
Independent leak-test samples: Cell A passed 470 of 500 pouches; Cell B passed 486 of 510. The selected parameter is difference between proportions.
Read the estimate and bounds
Cell A minus Cell B is −0.01294: about −1.29 percentage points. Its nominal 95% Wald interval is −0.04071 to +0.01483, or −4.07 to +1.48 percentage points.
Keep the interpretation clear
The interval crosses zero and includes differences in either direction. These samples do not establish equivalence. This normal-approximation interval uses independent leak-test counts, not paired pouches or strength readings.
Use the uncertainty in the decision
Define the pass-rate difference that matters, then compare it with the whole interval. Plan a more precise study if the remaining uncertainty prevents the decision.
More details: read each result section
Complete result tables use six significant digits, as in Help.
Confidence interval
Parameter names the population quantity. The nominal confidence level is 95%. Wald is a normal approximation, so actual coverage can differ from 95%, especially with small samples or proportions near 0 or 1. Estimate is the sample-based value; Lower bound and Upper bound mark its uncertainty. Method records the calculation. The interval crosses zero and includes differences in either direction. These samples do not establish equivalence. This normal-approximation interval uses independent leak-test counts, not paired pouches or strength readings.
| Statistic | Value |
|---|---|
| Parameter | Difference between proportions |
| Confidence level | 0.95 |
| Estimate | -0.0129412 |
| Lower bound | -0.0407098 |
| Upper bound | 0.0148274 |
| Method | Wald |
6. Create a report
Keep the complete Confidence interval table, selected parameter, confidence level, method and entered summaries. The interval crosses zero and includes differences in either direction. These samples do not establish equivalence. This normal-approximation interval uses independent leak-test counts, not paired pouches or strength readings.
Choose Add to report from the completed run. Open Choose individual items and advanced options to select tables and charts, then choose Add to draft. Hidden items stay in the saved analysis.
Name the report and add the purpose of the study and your interpretation. Choose Save, review Preview, then use Export → Download HTML. The example below contains the full selected content, including results beyond one screen.