TOPIC: 1 or 0 to start path the critical path

Will both methods to start the critical path be on the PMP? Rita starts with 0 and PMBOK starts with 1?

Hello James,

The specific questions that you get on the exam are random, and people who have taken the exam are ethically bound not to discuss any specific questions. However, that being said, I do have some general advice for you.

The important thing is that you know how to calculate critical path, and understand the formula set that you choose to use. So choose the one that makes most sense to you, learn it, understand it, use it, and stick with it. I think that it is unlikely that you will get into a situation where the method matters. The worst case scenario might be that you get a question with a pre-drawn network diagram that uses that other method, and you have to re-draw it.

I'm a fan of starting with zero. It simplifies the formulas, and it always made sense to me that you start with zero elapsed time. When you start a stopwatch, it starts at zero time, not at a value of 1.

Hopefully this addresses your concern.

Regards,
Steve

Hello James,
I agree with Steve's excellent post and I'm also in agreement with his preference for starting at 0. It just seems more natural to me.

I'll add one thing which helped me. Critical path can be defined as:

'The critical path is shortest duration in which the project can be completed'.

The project can be completed no sooner than the completion of your critical path activity.

The key for me was the word Duration. If your critical path is 9 time units long. If you started at 0 (9 - 0 = 9) or started at 1 (10 - 1 = 9), your duration is still 9.

I agree with Steve in the sense that the PMP Exam does not have a preference. And based on many discussions I've had with other PMP trainers over the years I have come to the conclusion that you will arrive at the correct answer, no matter if you use "0" or "1" during the exam.

However, I disagree with Steve on personal preference. I prefer to start with "1" because that makes more sense to me.

If you are a customer of our PMP Exam Formula Study Guide , then please take a look at the section titled "There are two approaches for calculating ES, EF, LS and LF" where we explain this preference in detail. (In a nutshell: First all modern scheduling tools start on day 1, and second when my boss tells me that my project starts on the first day of August, then that is August 1 and not August 0.)

So as you can see... using 0/1 is a matter of almost "religious preference" and the good news is that in this particular case the PMP Exam is agnostic.

Hi,

What if the question not showing you the starting activity or not me who decide to start with 0 or 1?
Can you check the picture please to be clear for you? This picture have small part of the critical path
The answer maybe 10 if we start with 0 or 11 if we start with 1….
It really makes me confused …please help

ya.k,

Please believe me when I say that you will not be facing this situation ON THE REAL EXAM.

You may see questions like this on the internet, but not on the actual exam. The real exam questions will be desined in such a way that it does not make a difference. They are not trying to trick you. They are trying to test your understanding.