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Can an event on the critical path have non zero slack time in critical path method?

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    $\begingroup$ What are you asking? I can build a GANTT chart with any kind of critical path slack you want, including negative slack. $\endgroup$ Mar 14, 2017 at 17:14
  • $\begingroup$ How is negative slack possible? $\endgroup$
    – user214671
    Mar 14, 2017 at 17:40
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    $\begingroup$ Just wait until you're in the real world. Some salesman will promise a product in 6 months. You have parts back-ordered for 4 months and require 2.5 months of assembly and quality test. result: negative0.5 months of slack. $\endgroup$ Mar 14, 2017 at 20:34

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The critical path is:

"the longest path of planned activities [...] to the end of the project"

Wikipedia

In what I would call "purely theoretical" Critical Path Analysis, the length of the project is the length of the critical path. Therefore tasks on the critical path have no slack by definition.

In the real world there may be external dates setting deadlines. Therefore although the critical path might take 15 months, if the deadline is not for 16 months, there would be 1 month of slack to tasks on the critical path. Similarly, if the deadline is in 14 months there is negative slack on the critical path.

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  • $\begingroup$ Thanks Andy! Did you mean 'the deadline might be 16 months'? If you meant what you wrote, can you please further explain? $\endgroup$
    – user214671
    Mar 14, 2017 at 16:26
  • $\begingroup$ I'm not convinced -- we always take the critical path as the one with the least slack, even if it's positive. $\endgroup$ Mar 14, 2017 at 17:15
  • $\begingroup$ Ok, fair enough. $\endgroup$ Mar 14, 2017 at 20:35

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