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Confidence Interval¶
Calculate confidence intervals for the mean, standard deviation, binomial proportion, or Poisson rate.
What is a Confidence Interval?¶
A confidence interval provides a range within which a population parameter is likely to fall at a specified confidence level (e.g., 95%). Quantum XL produces a whisker chart showing the lower and upper bounds with a center marker, plus a statistics table with the interval details.
Four CI Types¶
Four confidence interval types are available, each selected from a separate item in the Excel ribbon dropdown:
| Type | Distribution | When to Use |
|---|---|---|
| CI for the Mean | t-distribution | Estimate where the true population mean lies based on sample data |
| CI for Standard Deviation | Chi-squared | Estimate the range of the true population standard deviation |
| CI for Binomial Proportion | Beta (Clopper-Pearson exact) | Estimate the true proportion when data has exactly 2 outcomes (e.g., Pass/Fail) |
| CI for Poisson Rate | Chi-squared (exact) | Estimate the true rate of occurrence for count data (e.g., defects per day) |
Example Output¶
A typical output shows a whisker chart with vertical lines extending from the lower bound to the upper bound, a diamond marker at the center value, and a statistics table alongside with sample size, point estimate, and interval bounds.
Learn More¶
- Examples — Step-by-step tutorials for each CI type
- Preparing Your Data — Data types, column requirements, and the behavior matrix
- Options — Confidence level setting