How Risk Analysis Interprets Durations
In general, risk analysis interprets the value in the Original Duration field as the mode (most likely) value.
The way in which risk analysis interprets the value in the Original Duration field is determined by the distribution shape:
- For a uniform distribution, Open Plan ignores the value in the Original Duration field. Because a uniform distribution means that each possible value is equally likely, the concept of a mode value does not apply.
- For a normal distribution, Open Plan ignores the value in the Original Duration field for the purposes of risk analysis. Instead, Open Plan calculates the mode of the duration based on the values for optimistic and pessimistic durations.
- For triangular and beta distributions, Open Plan interprets the input value in the Original Duration field as the mode of the duration.
If you do not assign a probability distribution shape to an activity, Open Plan assumes that the duration of that activity is constant. Open Plan reads the value in the Original Duration field, ignores any values in the optimistic and pessimistic duration fields, and processes the activity during risk analysis the same as it would be processed during time analysis.
Example 1
You estimate that an activity can have a duration of 3, 4, or 5 days. Each duration is equally likely.
Enter the following duration probability information.
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Example 2
You estimate that an activity could have a duration anywhere between 10 and 30 days based on a normal probability distribution.
Enter the following duration probability information.
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Example 3
You estimate that an activity could have a duration anywhere between 10 and 30 days. You predict the most likely duration to be 12 days.
Enter the following duration probability information.
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Example 4
You know that an activity has a duration of 2 days.
Enter the following duration probability information:
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Related Topics
- Overview of Probability
- Using Risk Analysis
- Activity Details Risk Tab
- Probability in Durations
- Risk Analysis Output Files
- The Effect of Risk Analysis on Start Dates
- The Concept of Sampling Error
- How Risk Analysis Calculates Finish Dates
- Progress and Duration Probability
- Using the Risk Analysis Options Tab
- Using the Risk Analysis Advanced Tab