ABSTRACT
The sample mean, X ¯ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429124754/be33da89-95f5-45e7-a067-f2fa13b8eb97/content/eq1158.tif"/> , constitutes a so-called point estimate of the mean, μ, of the population from which the sample was selected at random. Instead of a point estimate, an interval estimate of μ may be required along with an indication of the confidence that can be associated with the interval estimate. Such an interval estimate is called a confidence interval, and the associated confidence is indicated by a confidence coefficient. The length of the confidence interval varies directly with the confidence coefficient for fixed values of n, the sample size; the larger the value of n, the shorter the confidence interval. Thus, for fixed values of the confidence coefficient, the limits that contain a parameter with a probability of 95% (or some other stated percentage) are defined as the 95% (or that other percentage) confidence limits for the parameter; the interval between the confidence limits is referred to as the confidence interval.
