Confidence Interval Precision

An analysis of confidence interval precision is analogous to a traditional power analysis, with CI Half-Width taking the place of effect size and Prob(Width) taking the place of power. The CI Half-Width is the margin of error associated with the confidence interval, the distance between the point estimate and an endpoint. The Prob(Width) is the probability of obtaining a confidence interval with at most a target half-width.

The POWER procedure performs confidence interval precision analyses for t-based confidence intervals for one-sample, paired, and two-sample designs, and for several varieties of confidence intervals for a binomial proportion.