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Examples

Quick Start — CI for the Mean

Create your first confidence interval in less than two minutes.

This example shows how to calculate a 95% confidence interval for the population mean from a single column of numeric data.

Goal

Calculate a 95% confidence interval for the mean weight of a sample, estimating where the true population mean is likely to fall.

Sample Data

Download ConfidenceInterval_Mean.xlsx

Excel Protected View

When you open downloaded files, Excel displays a Protected View warning. You must click Enable Editing before you can use Quantum XL with the file.

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Alternatively, you can copy the sample data from the table below and paste it directly into a new Excel workbook.

Weight
152.3
148.7
155.1
149.8
153.4
150.2
156.0
147.5
154.6
151.9

Each row represents one weight measurement. Quantum XL will use the t-distribution to calculate a confidence interval around the sample mean.

Steps

  1. Launch the analysis

    From the Excel ribbon, select QXL Stat Tools → Analysis Tools → Confidence Interval → CI for the Mean.

  2. Select your data

    Select cells A1:A11 (the header row plus all 10 data rows).

  3. Configure the analysis

    In the Confidence Interval dialog:

    • Data Columns: "Weight" should be checked
    • Confidence Level: 0.95 (default)

    Click Finish to generate the confidence interval.

Result

Quantum XL creates a whisker chart showing the 95% confidence interval for the mean. The vertical line extends from the lower bound to the upper bound, with a diamond marker at the sample mean. The statistics table alongside shows:

  • Sample Size — Number of observations
  • Mean — The sample mean (point estimate)
  • Standard Deviation and Standard Error
  • Lower Bound and Upper Bound — The 95% confidence interval limits

More Examples

Ready for more? See these variations: