The program evaluation and review technique (PERT) is a project management system that resembles a dynamic flowchart of interrelated processes. It is used to coordinate diversified project elements and their respective influences on costs, time and each other. This technique provides a more adaptive overview of these dynamic elements than traditional static project charts and timelines. Originally developed for large scale military-industrial projects, the program evaluation and review technique is employed in large and small-scale organizations that require the coordination of resources, teams, costs and deadlines in order to achieve dedicated outcomes.
A PERT chart gives an overview of a project development process. In practice, the execution of tasks depends on ongoing project requirements, team decisions and other external constraints. The primary task when developing a PERT plan is determining the critical activities upon which all other activities depend. This is sometimes referred to as the critical path method (CPM).
The chart itself consists of three major elements — nodes, arrows and paths — put together in various tree formations. The nodes identify the project's key elements, such as a departmental review, a research and development trial or the public launch of a new product. These nodes are connected with arrows, and the arrows determine the sequence of stages through which a project will go. Some nodes will have multiple arrows dependent upon their outcomes, with either/or decisions or possibly simultaneous activities. The advantage is that the observer can see immediately which project elements will be influenced directly by a given node's processes.
The path of a project is not necessarily linear or static, as one might find in the neat vertical bars of a Gantt chart. A chain is only as strong as its weakest link, so a chart utilizing the program evaluation and review technique is only as timely as its longest path. This path represents the minimum timeframe for completion of a project; as such it is called the critical path. This path will be the area of most concern for a project manager dealing with unforeseen delays and unexpected costs.
In general, the PERT chart displays sequences of processes that might occur simultaneously or might depend on the completion of a previous task. By clear assessment of these nodes, a manager can better recognize potential problem areas and processes most likely to introduce “slippage” into even highly complex projects. By comparing paths of lesser importance to the critical path, managers can identify not only definite milestones and deadlines but also areas of "slack," which afford more wiggle room.
By forcing project managers to establish firm understanding of the critical elements in a project and oversee dependency relationships between nodes, the program evaluation and review technique provides for a clearer grasp of a complex project. It might result in greater team coordination, more efficient communication activities and more effective process or goal evaluation. Computers assist in analysis of more complex plans. Given clear start/finish times and goals, they process known elements using algorithms to output the most thorough forecast possible.
Given the complexity and dynamic nature of PERT planning, the best results might occur with proven industrial methods where processes and expectations are widely known. Unforeseen circumstances or difficulties, scope creep and butterfly effects cans sometimes make short work of any well-laid plan, however. A well-prepared project manager can use the program evaluation and review technique not only to coordinate a vast amount of elements but also to minimize the likeliest areas of risk in order to produce a successful project outcome.