Confidence Intervals

Definition

Confidence intervals are ranges of values calculated from sample data that are likely to contain an unknown population parameter with a certain level of confidence.

Related terms

Margin of Error: The margin of error is half the width of a confidence interval and represents how much we expect our estimate to vary from sample to sample.

Level of Confidence: The level of confidence determines how sure we want to be that our confidence interval contains the true parameter value. Common levels include 90%, 95%, and 99%.

Sample Size: Increasing sample size generally leads to narrower confidence intervals because more data reduces uncertainty.