Best Practice: Graded Approach
Model evaluation should be conducted using a graded approach that is adequate and appropriate to the model application or decision at hand (EPA, 2009a).
A graded approach recognizes that model evaluation, as an iterative process, cannot be designed in a 'one size fits all approach.' Further, the NRC (2007) recommends that model evaluation be designed to the complexity and impacts (of the model) in addition to consideration of the life-cycle stage of the model and the evaluation history.
For example, a screening model (a type of model designed to provide a "conservative" or risk-averse answer) that is used for risk management should undergo rigorous evaluation to avoid false negatives, while still not imposing unreasonable data-generation burdens (false positives) on the regulated community.
Ideally, decision makers and modeling staff work together at the onset of new projects to identify the appropriate degree of model evaluation.