The Program Evaluation and Review Technique (PERT) is a statistical project management tool designed to analyse and represent the tasks involved in completing a project. It is particularly effective for large-scale, complex, and non-routine initiatives—such as Research and Development (R&D)—where task durations are uncertain.
Overview of PERT
- Purpose: To identify the critical path and the minimum time required to complete a project.
- Core Mechanism: Uses a three-point estimation method for each task:
- Optimistic time (O): The shortest possible time.
- Most likely time (M): The most realistic duration.
- Pessimistic time (P): The longest time if major setbacks occur.
- Formula: The Expected Time (
) is calculated as
- Visualisation: Tasks are represented as nodes (circles or rectangles) and dependencies as arrows.
Timeline History by Era
The history of PERT is defined by its transition from a secretive Cold War military tool to a foundational standard in global project management.
1. The Era of Inception (1956–1959)
This era was marked by the urgent need for a massive deterrent during the Cold War.
- 1956: The Polaris Project (Fleet Ballistic Missile program) began, facing the immense challenge of building nuclear-powered submarines capable of launching solid-propellant missiles.
- 1958: PERT was officially developed by the U.S. Navy Special Projects Office, specifically by Charles E. Clark. It was initially called “Program Evaluation Research Task”.
- 1958: Around the same time, the Critical Path Method (CPM) was independently developed by the DuPont Corporation.
- 1959: The technique was renamed to “Program Evaluation and Review Technique”.
2. The Era of Expansion & Mandates (1960–1975)
During this period, PERT moved from military use into government mandates and international visibility.
- 1960: The Polaris program, managed via PERT, achieved its first successful underwater launch and was completed 18 months to two years ahead of schedule.
- 1962: The U.S. Department of Defense mandated the Work Breakdown Structure (WBS) as part of the PERT approach for all future projects of this size.
- 1965–1968: One of the first large-scale civilian applications of PERT occurred during the planning of the Winter Olympic Games in Grenoble, France.
- Late 1960s: PERT was adopted by major public programs globally, including the UK’s nuclear power programs and Sweden’s fighter jet development.
3. The Era of Professionalization (1976–1999)
Project management began to coalesce into a formal academic and professional discipline.
- 1987: The Project Management Institute (PMI) published the first PMBOK Guide (Project Management Body of Knowledge), which included and standardised PERT and CPM concepts.
- 1989: Earned Value Management (EVM), which grew out of early PERT/Cost frameworks, became a mandatory part of U.S. government procurement.
- 1998: The PMBOK Guide was recognised as a standard by the American National Standards Institute (ANSI).
4. The Modern Era (2000–Present)
PERT has transitioned from hand-drawn charts to being integrated into digital ecosystems.
- 2000s: PERT concepts became core features in project management software (like Microsoft Project), where the math is often automated behind the user interface.
- 2020s: Emerging trends include AI-enhanced estimations, where machine learning algorithms analyse historical project data to generate the optimistic, pessimistic, and most likely time estimates more accurately than human experts.
Program Evaluation and Review Technique (PERT) Timeline by era and year
PROject Templates 