A Formal but Non-Automated Method to Test the Sensitivity of System Dynamics Models

摘要

Sensitivity testing of parameters can add greatly to the validity of a system dynamics model. Most model builders view parameter sensitivity tests as confirming whether a small perturbation to a parameter's numerical value results in a significant change in the model's behaviour. The results of these tests can indicate the level of accuracy that is required when assigning numerical values to a model's parameters, and also narrow down the search for improved policy. It can be impractical to run a sensitivity analysis on a trial and error basis because of the large number of permutations that exist. There are various strategies for approaching the sensitivity-testing task and these are reviewed. A formal and straightforward process for analysing the sensitivity of system dynamics models is proposed. A range of single parameter sensitivity tests is performed on all model parameters. Static and behavioural performance measures are compared using Spearman's Rank Correlation Coefficient to measure the congruence between the results of the separate tests.