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Quality Control and Quality Assurance in the Laboratory

The maintenance of high laboratory standards rests on a foundation of sound quality control (QC) and quality assurance (QA). Quality control and quality assurance refer to related but distinct components of a laboratory's effort to deliver a quality product (ANSI/ASQC A3-1978). Quality control refers to measures that are taken to ensure that the product, in this case a DNA-typing result and its interpretation, meets a specified standard of quality. Quality assurance refers to measures that are taken by a laboratory to monitor, verify, and document its performance. Regular proficiency testing and regular auditing of laboratory operations are both essential components of QA programs. QA thus serves as a functional check on QC in a laboratory. Demonstration that a laboratory is meeting its QC objectives provides confidence in the quality of its product.

Current QC and QA Guidelines

The 1992 report (NRC 1992) outlined many features of desirable QC and QA as part of a proposed regulatory program (p 104-105):

·      ''Individual analysts have education, training, and experience commensurate with the analysis performed and testimony provided.

·      "Analysts have a thorough understanding of the principles, use, and limitations of methods and procedures applied to the tests performed.

·      "Analysts successfully complete periodic proficiency tests and their equipment and procedures meet specified criteria.

·      "Reagents and equipment are properly maintained and monitored.

·      "Procedures used are generally accepted in the field and supported by published, reviewed data that were gathered and recorded in a scientific manner.

·      "Appropriate controls are specified in procedures and are used.

·      "New technical procedures are thoroughly tested to demonstrate their efficacy and reliability for examining evidence material before being implemented in casework.

·      "Clearly written and well-understood procedures exist for handling and preserving the integrity of evidence, for laboratory safety, and for laboratory security.

·      "Each laboratory participates in a program of external proficiency testing that periodically measures the capability of its analysts and the reliability of its analytic results.

·      "Case records—such as notes, worksheets, autoradiographs, and population data banks—and other data or records that support examiners' conclusions are prepared, retained by the laboratory, and made available for inspection on court order after review of the reasonableness of a request."

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