What is Program Evaluation Review Technique (PERT)?
The Program Evaluation Review Technique, or PERT, is a visual tool used in project planning. Using the technique helps project planners identify start and end dates, as well as interim required tasks and timelines. The information is displayed as a network in chart form.
PERT helps project planners identify:
- Start and end dates
- Anticipated total required completion time
- All activities, referred to as events on the chart, that impact the completion time
- The required sequence of events
- The probability of completion by a certain date
The PERT Process
PERT has a set series of steps in mapping out a complex project, which include:
- List all the tasks and milestones (a.k.a. events) required for completion of the project
- Determine the required sequence of tasks
- Design a chart to visually display all the steps
- Estimate the time required for each task
- Identify the critical path – the longest series of tasks in the project
- Adjust the chart to reflect progress made once the project starts
A PERT chart uses numbered circles or rectangles to represent milestones and straight lines with arrows at the end to represent tasks to be completed. The direction of the arrows, and the numbers, indicate the required sequence. Typically, the numbers increase by 10 at each milestone, so that new tasks can be added along the way without requiring the whole chart to be redrawn and numbered.
PERT was developed by the U.S. Navy in the 1950s to help coordinate the thousands of contractors it had working on myriad projects.
While PERT was originally a manual process, today there are computerized PERT systems that enable project charts to be created quickly.
The only real weakness of the PERT process is that the time required for completion of each task is very subjective and sometimes no better than a wild guess. Frequent progress updates help refine the project timeline once it gets underway.