Tuesday, July 23, 2013

Of slack and buffers

If you're like me, when you went to PM school one of the exercises was to hand calculate the critical path in a PDM schedule network. I think I even had such a problem on my PMP exam -- back in the last century.

And of course the question is begged: "what's a critical path?" . Quiz follows:
  1. Is it the most important string of tasks (judged by project objectives)?, or
  2. Is it the path with no slack?
And the answer is "2". And, by the way, the critical path could be a no-slack path of least important tasks -- critical but unimportant!

Fair enough -- but what about the "we've got slack" paths? If they are potentially important but not critical what is the management protocol to be applied?

Protocol choices for slack
There are two choices:
  1. Start everything as soon as possible with finish-to-start precedence
  2. Start everything as late as possible
Another way to state these protocols is:
  1. Smart
  2. Dumb
Or, how about this rendering?
  1. All risk is in the future; issues are in the present
  2. All risk is now and the future is certain
Or yet another:
  1. Action
  2. Procrastination
It seems patently obvious to not plan your project as a latest start, flipping the whole "cone of uncertainty" thing on its head... but it happens!

In a recent blog, I gave three ideas on planning... Your choice!

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