Project Schedule, P50 Anyone?

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Developing a schedule needs to be approached with success in mind. Dividing the project or portfolio into smaller manageable pieces called sub-projects is a good principle, a strategy acceptable and recommended in various industries. However, as the number of activity grows in the schedule, completeness, integration, and alignment challenges becomes the next hurdle. Key dates ends up not supporting each other. Probability of one activity finishing on time cancels out by the lower probability of another activity. This happens when sub-projects are not integrated and project portfolio fails to form a cohesive whole.

Disjointed schedule prevents the calculation of the correct critical path. The project that is able to develop a high quality, complete, integrated, and aligned schedule sets itself up for success. Part of the alignment process available is the use of P50 dates on all activities across the project portfolio. The purpose of synchronizing the probability to P50 is to increase achievability.

Any project is capable of generating a believable risk-based schedule baseline. Project confidence is higher when the team knows that the target schedule is achievable. It is also cheaper and more economical. Quantification assesses the overall schedule risk of a project. The schedule baseline becomes risk-based because risk probability and consequence are measured. I espouses the use of a P50 Risk-based baseline as the middle-ground although other synchronized schedule baselines such as P40, P60, or higher is possible.

A baseline deterministic schedule having activities with different, wide, and varying range of certainty causes major misalignments that are sometimes unseen to the untrained eyes. The story of two friends narrated in Sections 2.1 of the book "How to Create a Good Quality P50 Risk-based Baseline Schedule (Frago, R. 2015)" explains in simple terms what can happen. The person who is less certain being on time adversely affects activity of the other person. It will also influence some of their common activity.

The story of two friends (Figure 1) who have agreed to meet at a certain time to deliver something is a good illustration. One person has to undergo a complex maneuver to reach the meeting point and the other a considerably simple trip. Even if each person has the same point to point distance from the destination, it would be intellectual deceit to expect the two would come generally around the same time with the same certainty. The duration it takes for each one to be there given the same degree of effort will be different. If the two activities represented by the two individuals are interdependent, one will delay the others.

 

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If one activity depends on the other resource to be there before doing the next task, then the successor activity has to wait for the other resource to arrive, however long it takes. There is a big possibility of overall delay despite one hundred percent certainty of one person to deliver on time. This example supports the recommendation of an aligned P50 Risk-based baseline. Knowing that Pedro missed his plane bound from New York to Florida because the taxi driver is late in picking him up from his hotel is simple and so easy to appreciate.

Imagine a 5000 activity schedule with half of all its resource loaded activities have a calculated probability of less than 5% (<P5), yet the last milestone deliverable of the project says P60. The shortsighted conclusion is to expect completion on time by relying on the calculated 60% probability of the final milestone, or is it? When an activity is less than 5% probable, it is not possible to finish it on time. What would any thinking man expect looking at the other 2500 activities undermining each other? An activity delay is inevitable.

Since the project has 2500 unachievable activities influencing the other 2500, the successful of the P60 end date becomes questionable and less attractive. It is for this reason that this booklet of instruction is pulled together to address such disconnect. The solution is to come up with a synchronized probability of a middle ground target. Upon completing schedule risk quantification, we create an achievable P50 Risk-based baseline schedule. A P50 baseline has every activity date and duration at P50.

When data population increases, despite the randomness of available variables, the end-result is normal distribution. It is with this concept in mind that a P50 risk-based baseline holds a possible solution against the possibility of overrun. Preventing unachievable schedule is quite possible. In order to develop the P50 baseline, each of the activity making up the sub-projects has to be at a P50. Each of the sub-projects making up the projects portfolio has to be at a P50 as well. Instructions before the concluding section of this book describe in details how to create a P50 schedule.

Adjusting the probability of each sub-project schedule is simple. Changing final activity dates to reflect the P50 date is equally easy. In the past, identifying the right dates and duration to increase achievability is just a wish. This time it is different. The tool is available to convert all project activities to a P50 or any other probability value. The idea of a P50 supporting a P50 makes sense. It makes execution less stressful because the target is sound. The target becomes more achievable.



 

Rufran C. Frago, P. Eng., PMP®, CCP, PMI-RMP®

DATE: 29-Mar-2015

Note: The above article was last published in LinkedIn Pulse/Post on March 4, 2015

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