User's guide chapter 3 section 13 & 14

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3.13 – Scenarios: Setting Up Experiments

Scenarios are experiments that are run with a model in which the value of one or more parameters varies for each run. Scenarios allow you to run and compare multiple test cases for a model all automatically. You create scenarios by defining scenario parameters to be used in your model, referencing them in your model, and then defining specific scenarios in which values are assigned to those parameters.

3.13.1 – Scenario Parameters

Scenario parameters are placeholders like variables, only they are used to represent a value that changes from scenario to scenario. For example, if you want to run three model scenarios experimenting with different activity times, you would enter a scenario parameter as the activity time, and then define three different scenarios with three different times in the Scenarios tab of the Scenarios & Parameters dialog.

Scenario Parameters

New This button creates a new parameter that may then be edited.

Delete This button deletes the selected parameter.

Name The name of the parameter to be used in the model in place of actual values.

Default Value The value of the parameter when the Save & Simulate Chart menu item is selected rather than Run Scenarios.

Move Up Moves the selected parameter up in the list.

Move Down Moves the selected parameter down in the list.

How To – Define a scenario parameter

1. From the Simulation menu select Define Scenarios.

2. Click on the Scenario Parameters tab in the dialog (as shown on the previous page).

3. Click on the New button.

4. Enter the name of the parameter.

5. Enter a default initial value. This could be a specific number (e.g. number of resources) or a distribution function.

Hierarchical Model – Delete Scenario Parameters

Linked hierarchical model files synchronize data when you save each file. When you delete a variable, attribute, or scenario parameter in one model file, it is added back in from the other linked files during synchronization.

  1. Unlink your hierarchical model files.
  2. Make your change in each file and save it.
  3. Re-link the hierarchical structure

3.13.2 – Scenarios — Define Experiments

The Scenarios tab of the Scenarios & Parameters dialog allows you to define scenarios or experiments with different values for each of your selected parameters. It also allows you to disable specific scenarios to control which scenarios are run.

Define Experiments

New This button creates a new scenario.

Delete This button deletes the selected scenario.

Parameters This box lists the parameters and their defined start-up values.

Name The name of the scenario to be used in reporting statistics.

Value The value represents the scenario parameter for the selected scenario.

Disabled Disables the selected scenario, so that it will not be run during the simulation.

Set to Default