What's the Differences Between PERT and CPM ?

Abstract:

PERT (program evaluation and review technique) and CPM (critical path method) are both project management techniques that show the sequence of project activities. The main difference between them is their focus and application: 

Keywords

PERT (program evaluation and review technique),  CPM (critical path method), Planning, Organizing, Scheduling, Control Strategies 

Learning Outcomes

After undergoing this article you will be able to understand the differences between PERT and CPM 

PERT

A probabilistic model that focuses on minimizing project duration. It's used when the project's path is unclear and time estimates are uncertain, such as in research and development projects. PERT incorporates planning, organizing, scheduling, and control strategies. It uses network diagrams to represent the project structure, with arrows defining the sequence of activities and events. PERT analysis focuses on the arrows, not the nodes, and each event or milestone is joined by an arrow. 

CPM

A deterministic model that focuses on time-cost trade-offs and sticking to the schedule. It's used for projects with well-defined processes and repetitive tasks, such as construction and manufacturing. CPM is a statistical technique that assigns a start and end time to a project and focuses on scheduling and control. It uses precedence or arrow diagramming methods to represent the project structure, with the path defining the start to finish. CPM can help project managers develop realistic schedules, prioritize tasks, and identify potential delays early. 

The choice between PERT and CPM depends on the nature of the project and its specific requirements. In some cases, PERT and CPM can be used together to manage complex projects. 

Differences between PERT and CPM

Aspect	PERT (Project Evaluation and Review Technique)	CPM (Critical Path Method)
Abbreviation	PERT stands for Project Evaluation and Review Technique	CPM stands for Critical Path Method
Definition	A probabilistic tool for managing uncertain activities of a project	A deterministic tool for managing well-defined activities of a project
Orientation	Event-oriented, focusing on milestones and events	Activity-oriented, focusing on tasks and activities
Model Type	Probability-based, dealing with uncertainty in task durations	Deterministic, with fixed time estimates
Focus	Emphasises time estimation and meeting time targets	Emphasises time-cost trade-offs
Precision	Suitable for projects requiring high precision in time estimation	Suitable for projects where reasonable time estimation is enough
Sustainability	Suitable for projects with significant research and development	Suitable for industrial and construction projects

Conclusions

Both PERT and CPM offer unique advantages that enhance project management effectiveness. PERT excels in handling uncertainty and scheduling tasks, making it ideal for research and development projects. CPM, on the other hand, focuses on identifying and managing critical tasks, ensuring efficient long-term planning and resource allocation. When combined, these two project management techniques provide a robust framework for comprehensive project planning, project scheduling,, and control.

FAQs 

Q. What are the limitations of PERT and CPM?

Ans. :

While this tool can be very useful, the majority of respondents agreed that it has limitations, such as; PERT/CPM can become ineffective and difficult to manage if it is not well-defined and stable for active control of a project; PERT/CPM requires frequent updating and revising of calculations.

References

A Guide to the Project Management Body of Knowledge

Author: Project Management Institute, Mohammed Ahmad S Al-Shamsi

Project Management Absolute Beginner's Guide

Author: Greg Horine

Project Management for the Unofficial Project Manager

Author: Suzette Blakemore, Kory Kogon

Scrum: The Art of Doing Twice the Work in Half the Time

Author: Jeff Sutherland

The Lazy Project Manager: How to be Twice as Productive and Still Leave the Office Early

Author: Peter Taylor

Getting Things Done

Author: David Allen

Project Management for Non-Project Managers

Author: Jack Ferraro

The Five Dysfunctions of a Team

Author: Patrick Lencioni

Agile Project Management with Scrum

Author: Ken Schwaber

Strategic Project Management Made Simple: Practical Tools for Leaders and Teams

Author: Terry Schmidt

The fast forward MBA in project management

Author: Eric Verzuh

Project Management: Case Studies

Author: Harold Kerzner

Agile Project Management For Dummies

Author: Mark C Layton, Steven J. Ostermiller

Project Management for Humans: Helping People Get Things Done

Author: Brett Harned

The Deadline: A Novel About Project Management

Author: Tom DeMarco

Agile Practice Guide

Brilliant Project Management

Author: Stephen Barker, Rob Cole

Doing Agile Right: Transformation Without Chaos

Author: Darrell Rigby, Steve Berez, Sarah Elk

Project Management JumpStart

Author: Kim Heldman

Project Management: A Systems Approach to Planning, Scheduling, and Controlling

Author: Harold Kerzner

The Art of project Management

Alpha Project Managers: What the Top 2% Know That Everyone Else Does Not

Author: Andy Crowe

Advanced Multi-project Management: Achieving Outstanding Speed and Results with Predictability

Author: Kathleen M. Austin, Gerald I. Kendall