This paper documents the process used by the United States Environmental Protection Agency (USEPA) to estimate the mean and standard deviation of data reported by in-control drinking water laboratories during Water Supply (WS) studies. This process is then applied to the data reported for each specific sample, analyte, and method in ten WS studies, and linear relationships between the mean response and true analyte concentration and between the interlaboratory standard deviation of responses and true analyte concentration are presented. Such relationships can be invaluable as background information for anyone who must conduct an interlaboratory study using the same methods to analyze similar interference-free samples or who must evaluate the analytical quality of such data.
Statistician, National Water Quality Assurance Programs Branch, Ecological Exposure Research Division, National Exposure Research Laboratory, Office of Research and Development, USEPA (retired),
Stock #: JTE12395J