User's Guide to  

RiskyProject Professional

Define Distributions for Start Time, Cost, and Duration

You define distributions for duration, start time, and cost in the Distributions tab of Task Information dialog box. Distributions do not affect the baseline calculation. You cannot define distributions for summary tasks.

The Distributions tab allows you to assign distributions and define the meaning of low and high values for normal and lognormal distributions. The actual values for low, base (most likely), and high duration, cost, and start time are defined when you enter task parameters in data sheets. Low and high duration and start time can be entered in General tab of Task Information dialog box of in data sheets. Seeds, which are associated with the distributions, are defined in data sheets.

Click here for the list of RiskyProject distributions

To define task distributions:

1. Select the task in which you want to define distributions.
2. Open the Task Information dialog box. See the About Task Start Time, Finish Time, and Duration topic to read more about opening the Task Information dialog box.
3. Click the Distributions tab.
4. Select the Cost, Duration or Start Time tab.
5. Select the distribution from the Distribution list. Undefined means that the base value is used in all iterations.
6. Define the distribution parameters. The Probability Density chart is automatically updated. You can adjust distribution parameters using the sliders.
7. If you use a custom or discrete distribution, a grid opens. The grid will allow you to define points (or intervals for discrete distributions) and associated with each point (interval):
8. If you select Normal or Lognormal, you must select the Low and High probability range (P1 and P99, P5 and P95 or P10 and P90). These are “cut-off” parameters; meaning that duration, cost, or start time cannot go beyond these values.

Notes: 

• The Probability Density chart’s colors are consistent with those found in the Project Summary and Monte Carlo Simulation Results: Duration is blue, Cost is green, and Start Time is yellow. 
• Double-click on the probability density chart to enlarge it.
• To copy the chart to the clipboard or as a JPEG file, right-click and choose a copy command from the shortcut menu. 
  

Tip: 

In most real life examples, the type of distribution (triangular, normal, and lognormal, etc.) may not significantly affect the results of calculation. Results of project scheduling cannot be accurate with high precision due to the large systemic errors of estimation in project management. It is recommended that you assign different statistical distribution if you have reliable historical data about similar tasks.