External verification provides the main mechanism for independent evaluation and review of environmental models implemented by the Agency. It should include an examination of the numerical technique in the computer code for consistency with the conceptual model and governing equations. For more general information on how EPA develops and evaluates models, see the EPA document Guidance on the Development, Evaluation, and Application of Environmental Models. The linked copy includes some yellow highlighting of text used in this website for describing peer and verification reviews.

Independent testing of the code once it is fully developed can be useful as an additional check of integrity and quality. The purpose of external verification is verification that the code has no inherent numerical problems while obtaining a solution. Mechanisms of external verification includes code verification to make sure the code performs according to model design specifications.

The PRG calculator results were verified by external entities by conducting a numerical verification of calculator results.

This calculator has not been externally verified yet.