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LFR Levine-Fricke <br /> assessment will provide an overall summary of data quality, defining acceptability or <br /> problems with accuracy,precision, sensitivity, and representativeness of the results <br /> with clear guidance to the data users (e.g., risk assessors) of the uncertainties in the <br /> data that have been qualified as estimated(J) and a quantification of these uncertainties <br /> (e.g., bias high by a maximum of 80%)wherever possible. <br /> G1.3.3 Data Qualifiers <br /> During validation and assessment procedures, data results will be flagged with U.S. <br /> EPA CLP data qualifiers based upon QC criteria and best professional judgment. <br /> G1.4 Quality Control Review <br /> During data validation and assessment, results for QC sample analyses, including <br /> blanks, spikes, and duplicates will be evaluated as described below,using the <br /> Precision, Accuracy, Reproducibility, Comparability, and Completeness (PARCC; <br /> U.S. EPA 1994a)QC criteria defined below, to determine the validity and usability of <br /> the data. <br /> G1.4.1 Accuracy <br /> The determination of accuracy of a measurement requires knowledge of the true or <br /> accepted value for the signal being measured. It is a statistical measurement of <br /> correctness, and includes components of random error(variability due to imprecision) <br /> and systematic error(bias). It therefore reflects the total error associated with a <br /> measurement. Errors as they pertain to accuracy may result from several sources <br /> including the sampling processes, field contamination, improper preservation, handling <br /> of samples, sample matrix biases, and analytical procedures. A measurement is <br /> accurate when the reported value does not differ from the true value or the known <br /> concentration of the spike or standard. Accuracy will be calculated in terms of percent <br /> recovery of a known amount of a spiked compound according to the following formula: <br /> %R = [(Cs-Cn)/Csa]x 100 <br /> Page G-4 Final_RAP_Tracy_9.18.03(final).doaLFR <br />