Project Duration Forecasting

I've had a subscription to a trade rag called CrossTalk (The Journal of Defense Software Engineering) for a few years now. I've read the articles but none really got my attention and kept it. In the December 2008 issue, there is an article about comparing Earned Value Management Methods to Earned Schedule. It was written by Walt Lipke of the Oklahoma City Chapter of PMI. Now that I'm working on a very large government project, this article really sparked my interest. If you're working in a government PMO or on a government project, I recommend you give it a read. The author did a really good job of using real project data and also did an excellent job comparing EVM methods to the Earned Schedule (ES) prediction technique.

If you're new to Earned Value Management or still studying for your PMP, this may make your head hurt a little. If PVcum, EVcum, and BAC are in your daily vocabulary, you'll enjoy it. Article Link

Finding the critical path

PERT Critical Path Method includes determining the longest path in a network diagram and the earliest and latest an activity can start and the earliest and the latest that activity can be completed.  Here are a few basic things you need to think about.

  • It is the longest duration path through a network diagram and determines the shortest time to complete the project
  • It helps prove how long the project will take
  • It helps the project manager determine where best to focus his or her efforts
  • It provides a method to compress the schedule during the project planning phase and whenever there are changes
  • It provides a method to determine which activities have float and can be delayed without delaying the overall project.

The easiest way to find the critical path is to identify all paths through the network and add the activity durations along each path.  The path with the longest duration is the critical path.