HomeTechniques and Tips@RISK DistributionsCombining Estimates from Several People

3.17. Combining Estimates from Several People

Applies to: @RISK 5.x–7.x

Several people gave me their assessments of the likely impact of a risk or a benefit, but naturally their estimates vary. Also, I have higher confidence in some opinions than others. How can I combine these assessments in @RISK?

We often say in ordinary language that we give more weight to one thing than another in making a decision, and it's the same in this situation. You want to set up a little table of weights and @RISK probability distributions, and the question then is how to give each distribution the appropriate weight. It would be easy to take the weighted average of the distributions, but that causes the extreme opinions to be under-represented. There are many possible approaches that don't have that problem, and the attached workbook shows four of them.

In all four cases, the combined function is wrapped in a RiskMakeInput function. That ensures that only the combined distribution, not the individual assessments, will show up in sensitivity graphs and figures.

Last edited: 2016-03-28

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