Confidence Interval

A confidence interval is a range of values, derived from a data set, that is likely to contain the true value of an unknown population parameter with a specified level of confidence, typically expressed as a percentage (e.g., 95% or 99%). The interval is calculated from sample statistics and gives an estimate of the uncertainty around a sample mean or proportion.

For instance, if a researcher surveys 100 people and finds that 60% support a particular policy, a 95% confidence interval might be calculated as 55% to 65%. This means that the researcher can be 95% confident that the true proportion of the population that supports the policy falls within this range.

In another case, if a medical study reports a 95% confidence interval for the average blood pressure of a certain population as 120 mmHg to 130 mmHg, it suggests that the researchers are 95% confident that the true average blood pressure lies within this interval.