File: ABSTRACT.TXT


                PEST Model-Independent Parameter Estimation
                             System Abstract

              Center for Exposure Assessment Modeling (CEAM)
   National Exposure Research Laboratory - Ecosystems Research Division
                 Office of Research and Development (ORD)
              U.S. Environmental Protection Agency (U.S. EPA)
                         960 College Station Road
                        Athens, Georgia 30605-2700

                               706/355-8400


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                                  Summary


  PEST is a model-independent parameter estimation package. Its model-
independence is based on the fact that it can communicate with any model
through the model's own input and output files. The model can be a single
executable program or a series of executable programs encapsulated in a batch
file.

  The parameter estimation algorithm used by PEST is based on a robust
variant of the Gauss-Marquardt-Levenberg method. However, PEST also includes
advanced regularization functionality which assists in the calibration of
highly parameterized models. It also includes a nonlinear predictive analyzer
that allows the calculation of the uncertainty associated with a particular
model prediction, while maintaining the model in a calibrated state.

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