Statistical Prediction Intervals for the Evaluation of Ground‐Water Quality

Factors for a normal distribution are given such that one may be 99% confident that the two‐sided prediction interval x̄+ rs or the one‐sided prediction interval x̄+ rs will contain all of the k future values, where x̄ and s are the sample mean and standard deviation obtained from n previous values. In the context of ground‐water monitoring, the future samples may represent new monitoring values at each of k downgradient wells, and the n previous values might be the historical monitoring results for one or more upgradient wells. The Tables provided in this paper allow the computation of one‐sided and two‐sided 99% prediction intervals for previous sample sizes of n = 4 to 100 and future samples of k = 1 to 100. Modification of these intervals for log‐normally distributed data is also presented.