PERT stands for the Project Evaluation and Review Technique, and is a graphical tool used to schedule, organize, and coordinate tasks. It’s often used in conjunction with the critical path project management method.
Task Sequencing and Durations
One of PERT’s key components is its use of nodes and arrows to represent task dependencies and sequences. Sequential tasks are indicated by connecting arrows, whose lengths also correspond to the tasks’ projected duration. Using these tasks sequences, project managers can identify and prioritize the critical path and plan the fastest possible route to project completion.
But where other planning diagrams use best-case scenarios in the planning phase, PERT takes a more skeptical and realistic approach. Each task in PERT has three time estimates: Optimal, Normal, and Pessimistic. These are used to compute for Expected Time, with the formula (O + 4M + P) ÷ 6. The result is then plugged into a visual chart such as the PERT diagram or even a Gantt chart. This way, the project manager has a more accurate overview of the project life cycle.
Pros and Cons
As already mentioned, PERT makes it easy to identify the critical path and the relationship between each tasks start and end dates, as well as the available slack for each path. And because you have a better understanding of each path’s dependencies, you can more easily shuffle tasks around to facilitate better resource management.
One of PERT’s biggest drawbacks, however, is its tendency to grow unwieldy the more complex a project is. Some larger projects can have literally hundreds of tasks and dozens of paths, each with their own intersecting dependencies. When these complex diagrams become tangled and inconvenient, people stop using them—making them moot. Also, it’s hard to track elapsed time or project progress with PERT diagrams.
Some project managers use a combination of Gantt charts and PERT diagrams. The Gantt charts track and manage project progress and scheduling, while the PERT diagram tracks task dependencies and the critical path.
As with every other project management tool, what to use depends on your organization’s unique situation and workflow. If no single project management method works for you, mix and match them. The only truly “correct” project management method is the one that helps you get your work done the fastest.