Advanced Simulation Methods

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Advanced Simulation Methods

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This chapter describes how to:

       Setup and use Save Lists
Run Sensitivity Simulations.
Define the payoff function.
Specify search parameters for Optimization.
Set Optimization options.
Interpret and use the output of Optimization.
Use the Kalman Filtering function in Vensim.

Note that some of the material in this chapter is advanced in nature, and its discussion presumes familiarity with probability and statistics.

The material in this Chapter is not applicable to Vensim PLE and the optimization and Kalman Filtering discussion is applicable only to Vensim Professional.

Overview

To do a sensitivity simulation you must specify a set of constants to change and a Save List which is a set of variables to save values for.  To do an optimization you must specify a set of parameters to search over and create a Payoff Definition that determines how good an individual simulation is.  

The Save List and Payoff Definition are also useful elsewhere.  In addition to sensitivity simulations a Save Lists can be used when exporting data and when performing simulation or gaming with very large models.  A Payoff Definition can be used with a regular simulation to give a summary number for the simulation and optionally report summary statistics.

Because of this dual purpose in this chapter we first discuss Save Lists, then Sensitivity Simulation even though when you perform a Sensitivity Simulation from the Toolbar you will first define the Sensitivity Control parameters and then define the save list.  Similarly, we will first discuss Payoff Definitions, then optimization even though when you can setup Payoff  Definition files by starting the Optimization wizard from the Toolbar.