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TOPIC: Critical Path Method

Critical Path Method 6 years 3 months ago #8608

  • Michael Thompson, PMP
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I am having an extremely difficult time differentiating the Critical Path - forward pass.

In some books / examples the START ES is 0, some is 1. In some examples when you carry over the LS to the successor activity into the ES, you add 1, some do NOT. I study one way and then when I find the opposite example in a study question I am completely thrown off.

Anyone who can dumb this down so even a caveman can understand it, I would greatly appreciate it!
Thank you,

Critical Path Method 6 years 3 months ago #8610

  • Ahmed Amin
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Hello Michael,
I can understand the conflict you are facing, don't worry somehow it is common.

as for whether to start by 0 or 1, the most common is to start by 1 so you need to start by 1 in all cases except unless the question states otherwise.

below is a step by step on how to go through the forward pass:
1- The ES of the first activity in the path is 1. The EF of any task is its ES plus its duration minus one EF = ES + Duration - 1.
2- Now move forward to the next activity in the path. To figure out ES, take the EF of the previous task and add one. So ES = EF(of the previous activity) + 1, and EF = ES + Duration - 1.
3- If an activity has two predecessors, Which one do you use to calculate EF? use the one with the latest (larger) EF.

hope this clears your confusion.
Ahmed Amin Abdullah, PMP
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