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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 with <br /> clear guidance to the data users (e.g., risk assessors) of the uncertainties in the data that <br /> have been qualified as estimated (J) and a quantification of these uncertainties (e.g., bias <br /> high by a maximum of 80%) wherever possible. <br /> A1.3.3 Data Qualifiers <br /> During validation and assessment procedures, data results will be flagged with U.S. EPA <br /> CLP data qualifiers based upon QC criteria and best professional judgment. <br /> A1.4 Quality Control Review <br /> During data validation and assessment, results for QC sample analyses, including blanks, <br /> spikes, and duplicates will be evaluated as described below, using the Precision, <br /> Accuracy, Reproducibility, Comparability, and Completeness (PARCC; U.S. EPA <br /> 1994c) QC criteria defined below, to determine the validity and usability of the data. <br /> A1.4.1 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 accurate <br /> when the reported value does not differ from the true value, or known concentration of <br /> the spike or standard. Accuracy will be calculated in terms of percent recovery of a <br /> known amount of a spiked compound according to the following formula: <br /> %R = [(Cs-Cn)/Csa]x 100 <br /> Where: <br /> %R: percent recovery <br /> Cs:measured concentration in spiked aliquot <br /> Cn: measured concentration in unspiked aliquot <br /> Csa:actual concentration of spike added <br /> Accuracy will be evaluated based upon percent recoveries of the internal standards, <br /> matrix MSs, MSDs, system monitoring compounds, and surrogates for VOC analyses. <br /> The following are specific guidelines for the usability assessment of QC results that give <br /> an indication of the accuracy of the sample data. <br /> Page 4 Tracy-quly-samp-rpt-wrkpin(finap:JEE <br />