The Program Evaluation and Review Technique (PERT) is a scientific management tool designed to assist in planning and controlling projects. It helps to minimize interruptions and delays in processes involving interrelated functions, thereby reducing the time required for project completion.
Application of PERT
Key Components of PERT
- Events (or Milestones): Key points marking the start or end of one or more activities.
- Activities: Tasks required to move from one event to another. They consume resources and time.
- Network Diagram: A graphical representation of the sequence of activities and events, showing the flow from start to finish.
- Time Estimates: PERT uses three types of time estimates for each activity:
- Optimistic Time (O): The shortest time in which the activity can be completed.
- Pessimistic Time (P): The longest time the activity might take.
- Most Likely Time (M): The best estimate of the time required to complete the activity, assuming everything proceeds as usual.
Time Calculation in PERT
The expected time \( E \) for each activity is calculated using the formula:
Steps in PERT
- Define the Project and List Activities: Break down the project into individual tasks.
- Establish the Sequence of Activities: Determine dependencies and order of tasks.
- Construct the Network Diagram: Connect activities based on their dependencies.
- Estimate Time for Each Activity: Use the three time estimates to calculate the expected time.
- Determine the Critical Path: Identify the longest path through the network, which dictates the shortest possible duration for project completion.
- Update and Review the PERT Chart: Periodically review progress and update the PERT chart accordingly.
Historical Context of PERT
PERT was developed in 1958 by the United States Navy in collaboration with Booz Allen Hamilton for the Polaris missile project. It was created to manage and coordinate large-scale, complex projects which had high uncertainties and needed thorough planning and control.
Applicability of PERT
- Project Management: Ideal for large and complex projects with many interrelated tasks.
- Research and Development: Used in scenarios with significant uncertainties and dynamic changes.
- Construction: Helps in scheduling and controlling the various activities and resources.
Comparison with Critical Path Method (CPM)
While both PERT and CPM are used for project scheduling, they have distinct differences:
- Time Estimates: PERT uses probabilistic time estimates (optimistic, pessimistic, and most likely), whereas CPM uses deterministic time estimates.
- Focus: PERT is more focused on time variability and managing uncertainty, while CPM emphasizes cost control and time management.
Related Terms
- Critical Path: The sequence of project network activities which add up to the longest overall duration.
- Gantt Chart: A bar chart that represents a project schedule and shows the start and finish dates of elements.
FAQs
What are the benefits of using PERT?
- Enhanced Control: Provides better control over project schedules by identifying potential delays early.
- Time Optimization: Helps in identifying the shortest possible completion time.
- Resource Allocation: Aids in better resource management and allocation.
How does PERT handle uncertainties?
Can PERT be used for small projects?
References
- Meredith, J.R., & Mantel, S.J. (2012). Project Management: A Managerial Approach. Wiley.
- Kerzner, H. (2013). Project Management: A Systems Approach to Planning, Scheduling, and Controlling. Wiley.
- United States Navy Polaris Project Reports.
Summary
The Program Evaluation and Review Technique (PERT) is a valuable tool for project managers aiming to minimize delays and interruptions in complex projects. By providing a framework for planning, scheduling, and controlling, PERT optimizes the use of resources and time, and is adaptable to various industries and project sizes.
