Estimating the uncertainty of binary test results to assess their compliance with regulatory limits

摘要

A procedure to calculate the uncretainty associated to a binary response, of the type yeso, originated from an instrumental screening system, is described. Useful equations have been developed based on statistical intervals, and their validation were performed with standard commercial solution. It was applied to a differential pulse anodic stripping voltammetry (DPASV) screening system to analyse tap water, specifically, for determining Pb~(2+) and Cd~(2+) above the UE legislation limits, 10 and 5 #mu#g/l, respectively. A cut-off value from the responses of the calibratio samples is calculated and compared with the responses obtained for unknown samples. From this comparison, we will be able to take a compliance yeso decision, with an alpha probability of committing a type I error. Another parameter, r_screening, is calculated in order to compare different methods for the same screening application.