Running Models

Running a model lets you see how your model works and what happens when you make changes to it. There are a number of different ways users can interact with running models, see Stella Live™ for a discussion of displaying the entire simulation as changes are made.

There are also some differences between running a model from the model window, from the interface window and when published.

The following procedure is a high-level guide to the steps involved in running a model.

Steps for Running a Model

1. Specify the simulation length and unit of time.

   Use the Run Specs dialog box to select the unit of time for the run (for example, hours, days, weeks, months, etc.), to select the length of the simulation based on that unit (for example, 24 hours, 12 months, 4 quarters, 100 years, etc.), and to slow down the simulation's speed.

2. Select which modules and/or sectors to include in the run.

   If you're using modules or sectors in the model, you can choose to run the entire model, including all sectors and modules, or to run only selected modules and/or selected sectors. This lets you test components of your model to make sure they're working correctly, or focus your attention on a subsection of the model.

3. Make sure all variables are fully defined with equations and/or initial values.

   If you see a in any variable icon, it means that the variable isn't full defined.

4. Set up optimization or sensitivity analysis (optional).

   Sensitivity analysis lets you change one or more constants or initial values over multiple runs. Then you can view the results of the change in a comparative graph or table. Optimization lets you find a set of parameters that provide the best results toward achieving a target outcome.

5. Run the model.

   From the Model menu, choose Run (or click the button in the Run Toolbar).

See Also