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Data Validation and Verification
Historically, the term "validation" has been used to denote the systematic review of environmental chemical data. In CERCLA (Superfund) programs, the data are compared with the USEPA Contract Laboratory Program (CLP) Inorganic/Organic Statements of Work. In a similar manner, environmental data generated under RCRA are compared to Test Methods for Evaluating Solid Waste, SW-846. In both instances, qualifiers (such as U, J, or R) are added to the data. These data qualifier flags provide data users with information about the quality of the data.
Performance-based validation guidelines are now under review by the TCEQ. In the near future, all environmental data used in Texas for regulatory compliance, reporting, or to support risk reduction activities must be review using these guidelines.
The data validation process has been enormously successful in improving the quality of environmental chemical data. The review process only determines the quality of a data set and does not improve it. However, it is an audit program that has pushed the environmental laboratories to improve their procedure and their adherence to method requirements. Validation (as defined above) is the standard for data that are being collected under litigious or potentially litigious circumstances.
The data validation process focuses on the analytical data as generated by the laboratory. Often, little attention is given to the impact on data quality of other factors such as sample design or sample collection methods. Recent draft guidance from the EPA (Guidance for Quality Assurance Project Plans, EPA QA/G-5) has defined "validation" as the evaluation of the technical usability of generated data and "verification" as determination of adherence to SOPs or contractual requirements. It appears that the validation and verification process as defined by QA/G-5 and by Guidance on Environmental Data Validation and Verification, EPA QA/G-8 will focus on analytical data and not on other procedures such as sample collection and database management. The impact of non-laboratory procedures need to be addressed during data quality assessment (DQA.)
The following sources of information on data validation are available in PDF format:
Guidance on Environmental Data Validation and Verification EPA QA/G-8 -draft (epaqag8.pdf)
These documents are in PDF format. If you need a viewer for PDF files,
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Last update: April 15, 2005.