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1 <br /> ' Section 7 <br /> . ONSITE Environmental Laboratories Inc Revision 0 <br /> ' Quality Assurance Plan February 15, 1996 <br /> Page 2 of 4 <br /> ' > The close supervision of all operations by management and senior <br /> personnel <br /> ' When properly conceived and executed, a quality control program will result in a <br /> measurement system operating in a state of statistical control, which means errors have <br /> been reduced to acceptable levels and have been characterized statistically <br /> 7 1 3 Quality Assessment <br /> Assessment consists of the techniques used to assess the quality of the measurement <br /> ' process and the results Several tools are available for this process <br /> > A system of "control charts" is used to identify shifts, trends, and biases to <br /> track if the laboratory test is out-of-control Control charts are based upon <br /> Shewhart Charts and are continuing plots of data points from similar samples <br /> or processes over time They are used to determine if a system is in a state of <br /> ' statistical control Control charts are used to visualize and monitor the relative <br /> variability of repetitive reference materials, spiked samples, and the analysis of <br /> surrogates This variability is used to assess the accuracy, precision, and <br /> acceptability of measurements The ONSITE SOP for calculating and using <br /> control charts is available upon request <br /> i <br /> ' > Quality assessment is inherent in peer/super-visor review of data Data entry, <br /> manipulation, and reporting is reviewed by a second knowledgeable and <br /> professional party for errors, trends, consistency, and reasonableness <br /> ' Assembled data is reviewed and signed as approved by the appropriate <br /> supervisor before compilation into a final deliverables package Final review <br /> of the assembled deliverables package is performed by the laboratory <br /> ' Director <br /> > The Laboratory Director, the Quality Assurance Program Advisor, and outside <br /> auditors perform assessments of data quality through systems audits and <br /> proficiency evaluation samples <br /> > Blind QC Samples (External QC) are samples with a known value which are <br /> submitted to the laboratory as ordinary soil, sediment, or water Blind samples <br /> may include uncontaminated soil or solids, split samples, unlabeled duplicates, <br /> or performance evaluation samples <br /> 72 Evaluating Quality Control <br /> ' Evaluating both quality control and quality assessment consist of several <br /> characteristics, among them precision, accuracy, and completeness <br /> word b 0 loelscc7 doc <br /> 1 <br />