An Alternative Modeling Life-Cycle
A majority of modeling projects do not require the full development of a new model, but rather the application of an existing and established model. In this scenario, the model life-cycle would be shortened to involve model evaluation, application, and post-auditing.
Assesses a model's ability to provide valuable predictions of future conditions for management decisions.
In the modified life-cycle, a model is selected that meets the requirements of a specified problem. Once selected, a model may require calibration or different parameter values. Likewise, other qualitative evaluations of the model may further corroborate its application.
After the model has been applied, post-auditing can determine whether the model predictions were observed. The model post-audit process involves monitoring the modeled system, after implementing a remedial or management action, to determine whether the actual system response concurs with that predicted by the model.
Post-audits can also be used to evaluate how well stake-holder and decision-making roles were integrated during the development stages (Manno et al., 2008; EPA, 2009a). All of this information can further inform the model development team.
An Alternate Version of the Model Life-cycle: When model development is not required a modified version of the life-cycle is appropriate. If an existing model will work for the specified problem, model development (and design) is circumvented; leaving three steps to the life-cycle (shown above with dashed lines). The stages of the life-cycle defined by EPA (2009a) appear in the solid boxes. Recall that model evaluation occurs during the Development and Application Stages. (Click on image for a larger version.)