PLANET: A simulation approach to PERT

PLANET is a modification of PERT which permits use of arbitrary activity duration distributions in Monte-Carlo simulations which provide approximate distributions for completion times for project milestones and which identifies three classes of slacks for activities: total slack, free slack, and incremental slack (a new concept). The concept of “critical path” is supplemented by that of “probability of criticality” for each activity. This provides an improved basis for reallocation of resources using a “rob Peter to pay Paul” principle. The algorithms used are designed to have running times linearly proportional to the size of the underlying PERT network so PLANET should execute efficiently, even on large networks.