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3.10. Statistics for an Input Distribution

Applies to: @RISK 5.x–7.x

How can I place the mean or a given percentile of an input distribution in my workbook? Can I choose between simulation results and the perfect theoretical statistics?

@RISK has two sets of statistic functions that can be applied to inputs. The statistics of the theoretical distributions all have "Theo" in their names — RiskTheoMean( ), RiskTheoPtoX(), and so forth. You can get a list by clicking Insert Function » Statistic Functions » Theoretical. All the same statistics are available for simulated results; click Insert Function » Statistic Functions » Simulation Result.

The theoretical ("Theo") return the correct values before a simulation runs, during a simulation, and after a simulation, and they don't change unless you change the distribution parameters.

The simulation results (non-"Theo") change with each simulation, within ordinary statistical variability. Before the first simulation, they don't return meaningful numbers; during a simulation, they return #N/A. You can change them to be computed at every iteration, except in @RISK 5.0 — see "No values to graph" Message / All Errors in Simulation Data — but if you need those statistics during a simulation the better approach is usually to use the "Theo" functions.

Last edited: 2015-06-26

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