Method-Specific Precision and Bias Relationships Developed from Data Submitted During USEPA Wastewater Laboratory Performance Evaluation Studies

This paper documents the process used the United States Environmental Protection Agency (USEPA) to estimate the mean and standard deviation of data reported by in-control wastewater laboratories during Water Pollution (WP) studies. This process is then applied to the data reported for each specific sample, analyte, and method in ten WP 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.