KCE Glossary

A confidence interval is a statistical concept. It indicates how certain you can be that the true mean (or another parameter) of an entire population lies within a certain range, based on data from a sample.

Example
Suppose you measure the height of 100 people and find an average of 175 cm. You calculate a 95% confidence interval of 173 to 177 cm.
This means: "We are 95% sure that the true average height of the entire population lies between 173 cm and 177 cm.