THE FEUTEX TOOLKIT

Mean Confidence Interval from Summary

Construct a mean confidence interval from summary statistics and a supplied t critical value.

Statistics workspace● Runs in your browser

01 Your input

Sample meanvalueSample standard deviationvalueSample sizecountt critical valuenumber

02 Your result

View or copy raw result data

Result data

FormulaLower = mean-critical*sd/sqrt(n); Upper = mean+critical*sd/sqrt(n); Degrees Freedom = n-1

Sources and model references

https://www.itl.nist.gov/div898/handbook/eda/section3/eda352.htm

Worked example

Inputs

Sample mean: 20 value
Sample standard deviation: 5 value
Sample size: 25 count
t critical value: 2.0639 number

Expected results

Lower: 17.9361 number
Upper: 22.0639 number
Degrees Freedom: 24 number

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

Enter the labeled inputs using consistent units.
Check the stated assumptions and calculate.
Review each output and compare another input scenario.

Try this example

{
  "mean": 20,
  "sd": 5,
  "n": 25,
  "critical": 2.0639
}

Accuracy and scope

User supplies the correct t critical value for confidence level and n−1 degrees of freedom; independent approximately normal observations. Finite floating-point arithmetic; results can lose precision near singular or extreme inputs.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.