Project Management Consulting

Statistics Based Project Schedule

Have you seen project schedule that was built on a single point of duration on how long a task will take? Then, you saw a schedule that is flat out wrong and the project will not finish on the projected date. The only task that can have a finite duration that can be close to accurate is a task performed by a highly controlled machine. Otherwise, the duration can and will vary. Consider your commute time to work. Will your drive time to work across one month vary no more than 5 seconds? Have you tracked your drive time over 30 days so you can see the variance?

I ask the team members to give me their best case estimate (when all of the stars in the universe are perfectly aligned) for completing the task. I ask them to provide me an estimate for the most likely duration it will take them to complete the task. I then ask for their worst case estimate by considering past experiences of something taking longer than expected for unseen delays that are not catastrophically large.

I take these three estimates and load them into and run the Barbacana Full Monte Schedule Risk Analysis. It performs a monte carlo statistical analsis of the schedule and gives us the probability on the various completion dates of the project. With the probability in hand I work with the client to decide if that likelyhood of completing the project is acceptable or not. If the Full Monte analysis says the chance of completing the schedule on the desired date is for example 50%, and the client wants a schedule after the analysis to have a 90% chance to complete on that date, then we have to go back and replan which could include requiring additional resources to be added to the team to increase the probability to complete on a certain date. Another option can be cut scope make the project simpler. If you want to learn more details about the monte carlo analysis review the white papers I have on this. After the client agrees on the completion date with an acceptable probablity of completing on that date, the I move on with the team remaining activies I have listed on step 3 of planning your project.

Back to Home page