# Sensitivity Analysis (simulation)

Sensitivity analysis allows you to investigate the effect of varying
a fixed input or a distribution parameter for a simulated input over
a specified set of values. An independent set of simulated cases--effectively,
a separate simulation--is generated for each specified value, allowing
you to investigate the effect of varying the input. Each set of simulated
cases is referred to as an **iteration**.

**Iterate.** This choice allows you to specify the set of values
over which the input will be varied.

- If you are varying the value of a distribution parameter, then select the parameter from the drop-down list. Enter the set of values in the Parameter value by iteration grid. Clicking Continue will add the specified values to the Parameters grid for the associated input, with an index specifying the iteration number of the value.
- For the Categorical and Range distributions, the probabilities of the categories or intervals respectively can be varied but the values of the categories and the endpoints of the intervals cannot be varied. Select a category or interval from the drop-down list and specify the set of probabilities in the Parameter value by iteration grid. The probabilities for the other categories or intervals will be automatically adjusted accordingly.

**No iterations.** Use this option to cancel iterations for
an input. Clicking Continue will remove the
iterations.

To access the Sensitivity Analysis dialog

- From the Simulated Fields settings on the Simulation tab, select the input whose values you want to vary. If it is a fixed input, it must have a defined value. If it is a simulated input, it must have an associated distribution with defined distribution parameters.
- Click Sensitivity Analysis.