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TOPIC: Network diagram calculations - Confusion

Network diagram calculations - Confusion 6 years 4 months ago #1599

  • Elazar Lechtman
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Hi there

I'm writing my PMP exam on August 19th.

Anyway, there's some confusion in my head with regards to some of the network diagram calculations.

I'm lead to believe there are actually two methods to calculate ES, LF, ES etc etc

There is the American method which adds or subtracts 1 where applicable. This assumes that the start activity has ES, EF, LS and LF as 1.

There's also the "European" or alternative method which we as PM's use here which assumes the start activity has zeros for all values thereby not having to add or subtract 1 to any of the formulas.

Now my question is, is there any indication in the exam that would lead me into knowing which "method" is being utilised so that I can apply the right formula?

Thanks in advance.

Re:Network diagram calculations - Confusion 6 years 4 months ago #1600

  • Cornelius Fichtner
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You are correct, there are indeed 2 approaches, but I wouldn't call them "European" or "American". It's just a different way of doing it:

First approach: You calculate the network diagram starting on day 0

Second approach: You calculate the network diagram starting on day 1

I personally use the second approach, because when my sponsor tells me, that my project starts on the first day of September, then that is September 1 and not September 0. This is also the way that all modern scheduling tools seem to work. You schedule your project based on a calendar start date and not "on day 0".

That is why there is a slight difference between the calculations (you have to add/subtract 1 from the results in the 2nd approach). However, don't worry about this for the exam too much. The way that the question is formulated you should be able to identify how to go about this. Also: I understand that in most cases when you have to calculate this, it is the end result that is important and not how you got there.
Until Next Time,
Cornelius Fichtner, PMP, CSM
President, OSP International LLC
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