How is a confidence interval calculated?

Document ID

Document ID TE6455

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
How is a confidence interval calculated?
Summary
Calculation of confidence intervals.
Answer
The confidence interval is defined by determining an upper and lower confidence limit. These limits are calculated from t distributions.
To determine a confidence interval make a number of measurements on a sample and calculate the mean value of those measurements, this is estimating the actual value for the measurement of interest. Although this mean value represents the best estimate of the actual value, it is still only an estimate. Calculate a confidence interval for these measurements to express the precision of the estimated measurement.

A full series of calculations and examples for determining confidence intervals can be found attached to this article.

 
Attachments