Validating a process model
For example, is the logic in the conceptual model correct and are the model’s input-output relationships reasonable?If historical data exist (e.g., data collected on a system specifically for building and testing a model), part of the data is used to build the model and the remaining data are used to determine (test) whether the model behaves as the system does.Verification is an iterative process aimed at determining whether the product of each step in the development of the simulation model fulfills all the requirements levied on it by the previous step and is internally complete, consistent, and correct enough to support the next phase .
Validation is the process of determining the degree to which a simulation model and its associated data are an accurate representation of the real world from the perspective of the intended uses of the model .
Distinct from the specification for the model itself, this plan should provide guidance for each phase of VV&A and clarify the difference between the verification and validation phases. The plan should describe the method(s) used for validation, including any supporting analysis techniques.
If a data-driven approach is used for model validation, provide detail on either the pedigree of existing data or the plan to collect new data to support validation.
This technique can be used qualitatively—directions only of outputs—and quantitatively—both directions and (precise) magnitudes of outputs.
Parameters that are sensitive (i.e., cause significant changes in the model's behavior or output) should be made sufficiently accurate prior to using the model.
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It is extremely difficult to perform verification after the fact when normal system development artifacts have not been created and there is no audit trail from concept to product.