Distribution Types

Acumen includes three distribution types when modeling uncertainty. You can see the distribution type in the Type column of the S3 // Risk activity view or on the Activity Details Pane Duration Uncertainty tab.

The uncertainty values are displayed using both an absolute and a percentage value. If you change the one value, Acumen automatically recalculates the other. For example, if you change the percentage value, Acumen will automatically recalculate the absolute value as soon as you move off the field, and vice versa.

You can select a distribution type (shape) in the following areas:

• S3 Activities grid
• Risk Register
• Risk Events tab
• Duration Uncertainty tab
• Cost Uncertainty tab

Acumen calculates default values for the most likely duration and cost but you can edit them to skew the impact curve.

Shape Column Example:

Distribution Type	Description	See the values in these columns
Triangle	This type calculates minimum, most likely, and maximum remaining duration and is the default type.	Min Duration Most Likely Duration Max Duration Min Duration % Most Likely Duration % Max Duration %
Normal	This type calculates a mean remaining duration. The normal curve includes a standard deviation option that controls the width of the bell curve. The default is 1.	Mean Duration Mean Duration %
Uniform	This type calculates a minimum and maximum remaining duration.	Min Duration Max Duration Min Duration % Max Duration %
BetaPert	BetaPert is similar to a Normal distribution but it allows for positive or negative bias. While a Normal distribution is symmetrical on either side of the Most Likely value, with a BetPert distribution, the Most Likely value can be closer to the optimistic or pessimistic value. This type of distribution works best with activities that have reliable performance data.	Min Duration Most Likely Duration Max Duration Min Duration % Most Likely Duration % Max Duration %
TriGen	The TriGen distribution is similar to the Triangle but it allows you to also specify "nearly" or probable values. This distribution type helps to correct under reporting of extreme ranges because you build in a percentage probability that the distribution limits can be exceeded. When you use TriGen, you specify Minimum, Most Likely, and Maximum values as well as Lower and Upper Percentage. For example, if you specify 10 and 90 as the Lower and Upper Percentages, your Minimum is really the 10th percentile with the absolute minimum slightly below it and your Maximum is really the 90th percentile with the absolute maximum slightly above it.	Min Duration Most Likely Duration Max Duration Min Duration % Most Likely Duration % Max Duration % Lower Percentage Upper Percentage