whatIf? Wiki

During a simulation run, calculators in a model are run with given values for control variables to produce a set of outputs. Control variable values are saved as instances. Collections of instances are saved as scenarios. By using scenarios, a user can quickly recall a set of variable values used to create a given model output and can compare sets of values within different scenarios. The relationship among variables, instances, and scenarios is shown in the diagram below.

• An instance is a value for a variable.
• All variables must have at least one instance.
• Variables can have multiple instances.
• For a simulation run, variables use one and only one instance.
• Saved collection of instances is a scenario.
• Instances do not have to be used in any scenario.
• Worksheet reflects the current set of instances being used.