ICS-White Paper: When is the Critical Path Not the Most Critical Path


Pages: 37
Illustrations: 4
Bookmarked: Yes
Glossary Items: 24
Product Number: WPA-KK-14
Digital Format: Static PDF

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Introducing the Monitored Path Ranking System

Today, more than fifty years after the Critical Path Method made its debut, there still is no universally accepted definition for the central term, Critical Path. Among the dozens of more obscure definitions, two conflicting theories dominate scheduling glossaries: the Longest Path interpretation and the Least Total Float Path interpretation.

As this White Paper exposes in its opening pages, these two interpretations are deficient in three major ways:

  • From a practical perspective, they are incompatible with one another.
  • From a value perspective, they both prove incapable of actually identifying the typical Schedule’s several Critical Paths.
  • From a stability perspective, they are both based on a comparative platform that causes the Critical Path to shift and flicker uncontrollably with each corresponding change in Schedule content.

The problem goes much deeper than a lack of agreement on how to spot a Schedule’s Critical Path. Remarkably, there is virtually no discussion of the underlying words, “Path” or “Critical.” But even more astounding, as this White Paper concludes, the two prevailing definitions of a Critical Path (Longest Path and Least Total Float Path) share the same deficiencies:

*  They apply the word, “critical,” in a comparative manner. This leads to criticality instability.
*  They assume that a schedule has only one critical path. Most have multiple critical paths.
*  The conclusions one can reach, based on a single path/single goal theory, are equally limited.
*  They necessarily encourage limiting the number of date constraint imposed on the logic.

This White Paper proposes a refreshing alternative to the Critical Path concept, called the Monitored Path Ranking System. Here are some of its highlights:

  • Every Finish Date Constraint is being monitored; not just the last Finish Date Constraint, the one that corresponds to the final Deadline Milestone, Project Completion.
  • All Activity Paths leading to each Finish Date Constraint are being monitored; not just the one with the least Total Float or the one that appears to be the longest Activity Path.
  • Every Activity Path is measured and ranked according to a pre-defined scale that is equally applied to all Activity Paths in the Schedule. This provides for apples-to-apples comparisons across all Finish Date Constraints, across multiple Schedule Editions, and even across different Projects.
  • Since all Activity Paths that are linked to a given Finish Date Constraint are monitored and scored statistically, it is possible to compute an Achievement Probability Value for each Deadline Milestone.
  • By tracking a set of Achievement Probability Values for a single Finish Date Constraint, one can obtain a far better understanding regarding the effects of work progress on a given Deadline Milestone across time.
  • By comparing Achievement Probability Values across Deadline Milestones, it is possible to compute an overall Project Achievement Probability Value.
  • By comparing Achievement Probability Values across Finish Date Constraints, Project Management can easily recognize where managerial attention is most urgently needed. For instance, Project Achievement Probability Values can be compared across Projects within a Program (portfolio of Projects).
  • Because Activity Path labeling is no longer subjective or comparative, Activity Path ranking will remain more stable, less fluctuating.
  • Since every Activity Path will be recognized by a single Total Float value associated with it, Activities that reside on multiple Activity Paths will now be able to report the multiple Total Float values available to them.