Probability in Durations
With Open Plan, you can estimate the durations of any uncertain activities by using different types of information to create a probability distribution.
The following is needed to define a probability distribution for durations for any activity:
- Pessimistic duration
- Optimistic duration
- Duration
You can also define the shape of the distribution as follows:
- Uniform: Each outcome is equally likely.
- Normal: Probable outcomes cluster symmetrically around the center of the distribution.
- Triangular: Probable outcomes cluster around the mode value of the distribution. Outcomes close to minimum and maximum values of the distribution still possess a significant probability.
- Beta: Probable outcomes cluster around the mode value of the distribution. Outcomes at the extreme values of the distribution are very unlikely.
The ability to enter these parameters enables Open Plan to define very precisely the duration of some or all the activities in the project.
Example
Assume that you suspect an activity will take 10 days, but you want to allow for an uncertainty of ± 2 days in the duration. You would model this situation by entering the following values:
- Optimistic duration: 8 days
- Pessimistic duration: 12 days
- Original duration: 10 days
Related Topics
- Overview of Probability
- Using Risk Analysis
- Activity Details Risk Tab
- Risk Analysis Output Files
- How Risk Analysis interprets Durations
- 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