ProUCL Version 3.0 - Statistical Software to Compute Upper Confidence Limits of the Unknown Population Mean

The EPA Technical Support Center (TSC) in Las Vegas has developed ProUCL Version 3.0 software to support risk assessment and cleanup decisions at contaminated sites. Risk assessments, exposure evaluations, and cleanup decisions are often made based upon the mean concentrations of the contaminants of potential concern (COPCs). The true population mean concentrations of the COPCs at a contaminated site are often unknown, and are frequently estimated by the respective sample means based upon the data collected from the site under investigation. In order to address the uncertainties associated with the estimates of the true unknown mean concentrations of the COPCs, appropriate 95% upper confidence limits (UCLs) of the respective unknown means are frequently used in many environmental applications. The computation of an appropriate 95% UCL of practical merit depends upon the data distribution and the skewness associated with the data set under study. ProUCL can be used to compute an appropriate UCL of the unknown population mean using a discernible probability distribution (e.g., normal, lognormal, gamma) and/or a suitable non-parametric distribution-free method.