# Critical Path Method (CPM) The Critical Path Method (CPM), or critical path analysis, is a scheduling technique that finds the longest chain of dependent activities in a project. That chain, the critical path, sets the shortest possible duration of the whole project. CPM was developed in the late 1950s by Morgan R. Walker of DuPont and James E. Kelley Jr. of Remington Rand, around the same time as [[Program Evaluation and Review Technique (PERT)|PERT]]. To apply it, you need: - The list of activities (typically from a [[Work Breakdown Structure (WBS)]]) - The duration of each activity - The dependencies between activities - The end points: milestones or deliverables From these, CPM computes the earliest and latest start and finish of each activity. Activities on the critical path have no float (slack): any delay on them delays the project. Activities off the path have some float and can slip without moving the end date. The dependency network is a [[Directed Acyclic Graphs (DAG)|directed acyclic graph]]. The practical lesson holds even without the calculations: speeding up work that isn't on the critical path doesn't finish the project sooner. To move the end date, shorten the critical path or remove a dependency. Critical chain project management, introduced by Eliyahu Goldratt, is a variant that also accounts for limited resources and adds buffers. ## References - https://en.wikipedia.org/wiki/Critical_path_method - https://concepts.dsebastien.net/concept/critical-path-method/ - https://concepts.dsebastien.net/concept/critical-chain-project-management/ ## Related - [[Program Evaluation and Review Technique (PERT)]] - [[Work Breakdown Structure (WBS)]] - [[Directed Acyclic Graphs (DAG)]] - [[Program management]] - [[Project Management Body of Knowledge (PMBOK)]] - [[Project Management (MoC)]]