The results of the simulations are displayed in a table containing the forecast means, the uncertainty assumption values, and the statistics (including percentiles) of the forecast distribution for each simulation (Figure 81, 2D Simulation Results Table).
The tool also graphs the results of the two-dimensional simulations on an overlay chart and a trend chart.
The overlay chart preferences can be set to show the risk curves for the simulations for different sets of uncertainty assumption values. To do this, set the Chart Type for each series to Line and choose Cumulative Frequency view. It is convenient to use the chart hotkeys — Ctrl+t for the chart type and Ctrl+d for view. Optionally, use Ctrl+n to move or remove the legend and Ctrl+m to cycle through central tendency marker lines.
For this example, Figure 82, Overlay Chart of Risk Curves shows that most of the risk curves are clustered densely toward the center while a few outlier curves are scattered toward the Cumulative Frequency axis, showing the small probability of having a much greater risk.
In risk analysis literature, the curves are often called the alternate realizations of the population risk assessment.
The trend chart (Figure 83, Trend Chart of Certainty Bands) shows certainty bands for the percentiles of the risk curves. The band width shows the amount of uncertainty at each percentile level for all the distributions.
You can focus in on a particular percentile level, such as the 95th percentile, by viewing the statistics of the 95th percentile forecast, shown in Figure 84, 95th Percentile Forecast Statistics. For example, this figure shows 100 trials, the number of 95th percentiles in the forecast.
If you have the Probability Above A Value option selected in the Run Preferences, then Options panel, the percentiles will be reversed in meaning, so that the 1st percentile represents the uppermost 1% and the 99th percentile represents the lowest 1%. For more information, see Setting Statistics Preferences.
Compare the results of the two-dimensional simulation to a one-dimensional simulation (with both uncertainty and variability co-mingling together) of the same risk model, as in Figure 85, Forecast Chart for One-dimensional Simulation, following .
The mean of the 95th percentiles in Figure 84, 95th Percentile Forecast Statistics, 1.45E-4, is lower than the 95th percentile risk of the one-dimensional simulation shown in Figure 85, Forecast Chart for One-dimensional Simulation at 2.06E-4. This indicates the tendency of the one-dimensional simulation results to overestimate the population risk, especially for highly skewed distributions.
