Confidence Interval Definition

Definition: A specific interval estimate of a population parameter determined that uses data obtained from a sample and the specific confidence level of the estimate.

Interval of values bounded by confidence limits  within which the true value of a population parameter is stated to lie with a specified probability

A confidence interval (CI) is a particular kind of interval estimate of a population parameter and is used to indicate the reliability of an estimate. It is an observed interval (i.e. it is calculated from the observations), in principle different from sample to sample, that frequently includes the parameter of interest, if the experiment is repeated.


A confidence level of 90% (or .90) shows us that the likely-hood of the population being within the given interval is 90%.

Last Modified on February 9, 2013 by JoeStat

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