# One-way Rainbow Diagrams

A One-way Rainbow Diagram is an in-depth look at the effects of varying a single variable on the optimal policy and the expected value (and certain equivalent, if applicable). The full model is run each time with a separate setting of the sensitivity variable. Sensitivity analysis is only permitted for values initialized with a constant expression.

__Analyzing Rainbow Diagrams__

When the sensitivity runs are complete, DPL displays a graph with the model output (expected value or certain equivalent) along the vertical axis and the range of values for the sensitivity variable along the horizontal axis. This information is also printed to the Session Log.

Initially, DPL will graph expected value as a function of the sensitivity variable. To graph the certain equivalent, turn on the View | Results | CE button on the ribbon. (If you have not specified the use of a utility function, this button will not be greyed out.)

A region in which the optimal policy is the same is indicated with a single color. If there is more than one colored region in the graph, then the optimal policy is different depending on the value of the sensitivity variable. Because model outputs are determined at discrete values over a range of the sensitivity variable, you should not assume that the line between regions indicates the precise value at which the policy changes. If the precise point at which the policy changes is important, rerun the sensitivity analysis using a narrower range and smaller increments.

__Policy Information__

If Show Tips is turned on within View | Tips you will be able to view the expected value and policy information by hovering the mouse cursor over the markers displayed on the diagram. This information is also printed to the Session Log.

NOTE: If your model has a Halt function in the Objective Function or the Constraint Function, the Rainbow diagram will not display policy changes. (See Constraint Functions)

* Versions:* DPL Professional, DPL Enterprise, DPL Portfolio

*See Also*