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r <br /> f 4 <br /> f Stockton 99 Speedway - <br /> Quality Assurance Project Plan April 12,2007 <br /> 5.4.2 Accuracy <br /> Accuracy refers to the degree of agreement between a measurement or set of measurements to an <br /> accepted reference value. Accuracy is assessed by means of reference samples and percent <br /> recoveries. The calculation of percent recovery (%R) or accuracy is given by the equation: <br /> %R 100x IL5 —LI <br /> X <br /> Here, LS refers to the measured value of the spiked sample, L refers to the measured.value of the <br /> unspiked sample, and X refers to the known value of the spike solution. Acceptable levels of accuracy <br /> vary with the sample matrix, analytical method, and sample concentration. EPA accuracy data will be <br /> used as a basis for developing acceptance criteria for assessing precision. <br /> Field accuracy will be assed through the analysis of field equipment and trip blanks. The goal for field <br /> equipment and trip blanks is that all values are less than the reporting limit for each target constituent. <br /> 4 <br /> 5.4.3 Completeness <br /> Completeness is the amount of valid data collected as compared to the amount of data that was <br /> i expected to be collected under normal operating conditions. Two completeness values will be <br /> i calculated: total number of samples collected, and total number of samples reaching the laboratory in <br /> tact. The objective for completeness is to recover at least 90 percent of the planned data. The formula <br /> for completeness is: <br /> Number of valid results <br /> %Completeness= 100 x. Number of Expected <br /> Results <br /> QuaJky_M5 _Pro; ai�F na4.aoc 5-5 The Source Group,Inc. <br />