STR N421 - Lecture 7 - 2011

# Drmagedezzatgeorgy schedule schedule calculations the

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Unformatted text preview: ould take into account the network paths. Like typical scheduling, the critical path is associated with the highest calculated sum. Dr. Maged Ezzat Georgy Schedule Schedule Calculations The biggest issue we still need to address is how to deal with the more complex scheme (i.e., probability probability distributions) in adding up the numbers. To overcome this issue, we revert to the so-called “Central Limit Theory” in statistics. This theory addresses the summation of probability distributions. distributions. Dr. Maged Ezzat Georgy Schedule Calculations According to the “Central Limit Theorem”: ◦ The summation result is a “Normal Distribution”. ◦ Tsum (expected time for the project) = sum Σ te (longest path). ◦ Vsum (expected variance for the project) = Σ ve (longest path). ◦ σsum (expected SD for the project) Dr. Maged Ezzat Georgy = √ Vsum Back Back to the Project Network Again … te = 8, σe = 2 te = 5, σe = 1 te = 10, σe = 1.5 Tsum = 30 σsum = te = 10, σe = 2 √13 te = 20, σe = 3 te = 25, σe = 4 Dr. Maged Ezzat Georgy Probability of Completion PERT provides the means to calculate the probability of of completion by a certain time/date. An example … ◦ Probability of completing the project within 52 weeks is 80%. ◦ Probability of completing the project later than 52 weeks is is 20%. Dr. Maged Ezzat Georgy Probability Probability of Completion Now, how can we calculate this probability??? We use the z-tables as follows… ◦ First calculate Z, where Z = (X – Tsum) / where ◦ Then use the tables: enter with Z...
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## This document was uploaded on 01/22/2014.

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