HomeTroubleshooting@RISK for Excel: SimulationInput on Tornado Graph Is Not a Precedent

4.13. Input on Tornado Graph Is Not a Precedent

Applies to: @RISK 5.x–7.x

One or more of the bars on my tornado chart represents an input that is not a precedent of the output.

There are a couple of possible explanations.

Smart Sensitivity Analysis disabled

Do you have Smart Sensitivity Analysis enabled, on the Sampling tab of Simulation Settings?

If you do, then the simulation should only put actual precedents of the output as bars in the tornado. There's an important exception, however. If your model contains any of the features listed in Precedent Checking (Smart Sensitivity Analysis, then Smart Sensitivity Analysis is unable to trace all precedents of the outputs. @RISK will display a pop-up at start of simulation, telling you this, and asking your permission to proceed without Smart Sensitivity Analysis. Did you receive such a pop-up?

If you have Smart Sensitivity Analysis enabled, and you did not receive such a pop-up, then the overwhelmingly likely explanation is that a dependent relationship exists.

Excel 2007–2016 offer a tool to help you locate the relationship. Click into the output cell, then in the Formulas tab repeatedly click "Trace Precedents" until you find the input in question. Or, click on the input in question, then "Trace Dependents" until you find the output in question, or something you recognize as a precedent of the output in question. Which method is easier will depend on whether direct and indirect dependents of the input are more or less numerous than precedents of the output.

By the way, if there's a precedent or dependent on another worksheet, Excel will display a dotted line with a worksheet icon at the end. Click on the dotted line, not the worksheet icon, if you want to follow the relationship.

Duplicate input names

If you have two or more inputs with the same name, the one in the tornado might not be the one you think. Look in the Model Window to see if the name occurs more than once. If you're displaying inputs by category, first right-click in the table, select Arrange, and un-check Group Inputs by Category.

To sort the inputs by name, click on the gray Name column heading to sort inputs A–Z or Z–A. Then duplicate inputs will be next to each other. To change the name of an input, right-click it and select Function Properties.

Last edited: 2017-10-10

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