Difference Between CPM and PERT

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In this article, we will discuss on Difference Between CPM and PERT.



  1. Critical Path Method (CPM)  

Critical Path Method (CPM) is the best tool for scheduling the activities of a complex Project. It was introduced in 1950 by Morgan R. Walker of DuPont and James E. Kelley Jr. of Remington.

In CPM networks, the whole work consists of a number of clearly recognizable operations or jobs, called activities. Activities are major works that consume time to carry out, and on which resources are a cost.

Junctions between activities are term as events. The CPM networks are usually directed to activity-oriented diagrams in which an arrow indicates each operation, and the sequence of the arrows shows the series in which the operations are done.

For example, at a foundation construction project, the various activities may be; layout the foundation trench’, ‘excavating the foundation,’ ‘put sideboards,’ ‘concrete the foundation base,’ etc.

CPM network is commonly employed for repetitive kind tasks, or for those projects for which a relatively precise estimate of time for completion of each activity may be produced; and for which cost estimations may be prepared to employ a fair degree of accuracy.

For example, CPM is the very best choice for construction projects. But it isn’t a suitable choice for growth and research projects.


i. CPM Basic Steps

a. Choose the needed project.

b. List needed work in sequence.

c. Make a flowchart having each needed work.

d. Recognize all critical and non-critical relationships (paths) among the needed works.

e. Set a wished completion/execution time for each needed work.

f. Examine all critical relationships to decide all possible options or backups for as many as attainable.





  2. Program Evaluation Review Technique (PERT)  

PERT stands for Program Evaluation Review Technique 

This PERT approach first time introduced by the United States Navy in 1958, is majorly employed in conjunction with the critical path method in the year 1957 (CPM).

The approach was introduced by the Navy Special Projects Office in cooperation with Booz, Allen, and Hamilton, an administration consulting firm, also Lockheed Missile System Division for evaluating the feasibility of existing schedules on the Polaris missile program and for documenting advancement.

The PERT system employs a network diagram made of events that have to be specified to reach task purposes. An event is that particular instant of time when some detailed part of a plan is to be completed.

It denotes a point in time and does not need any resources. PERT employs event-oriented network diagrams in which arrows enter successive events.

For example, at a foundation construction project, the different events could be the foundation layout created,” the foundation excavated,” the sideboards fixed,” concreting completed’ etc.

The process of event orientation in the network diagram developed out of the wish to document the project’s advancement through discernible management milestones.


i. PERT Basic Steps

a. Determinating Works and Landmarks:

Each project concerns a series of needed works. These works are recorded in a table, allowing more details on timing and sequence to be added later.


b. Positioning the Works in a Suitable Sequence

The works have been inspected and positioned in a sequence to get the expected results.


c. Network Diagramming:

A network diagram is drawn with the workout sequence data displaying the sequence of concurrent and sequential activities.


d. Time Estimating:

Here can be the time needed to carry out each activity, in three parts:

i. Optimistic timing

The shortest time to complete an activity

ii. Most likely timing

The completion time has the highest probability

iii. Pessimistic timing

The longest time to complete an activity


e. Critical Path Estimating:

This specifies the entire time needed to complete a project.





  3. Difference Between CPM and PERT  



Difference Between CPM and PERT



1CPM Stands for Critical Path MethodPERT Stands for Program Evaluation Review Technique
2PERT is a technique of project management that is employed to arrange uncertain (i.e., time is not known) activities of any project.CPM is a technique of project management that is employed to arrange only certain (i.e., time is known) activities of any project.
3The CPM is a statistical approach to project management this is arranged well-defined works of a project.The PERT is a project management approach, employed to arrange uncertain works of a project.
4This CPM is a method to control cost and time.The PERT is a method for organizing and handling time.
5CPM Method orientation like Activity-orientedPERT Method orientation like Event-oriented
6In the CPM method evaluation of Evolved as a Construction Project.In this method evaluation of Evolved as a Research & Development project
7Model type DeterministicModel type Probabilistic.
8This method focuses on Time-cost optimization.This method focuses on Time control.
9It  single time estimateIt is a three-time estimate.
10Suitable for Reasonable time estimateSuitable for High precision time estimate
11Management of Predictable activitiesManagement of Unpredictable Activities
12Nature of jobs Repetitive natureNature of jobs Non-repetitive nature
13Critical and Non-critical activities are DifferentiationCritical and Non-critical activities aren’t Differentiated
14Employ in Research and Development ProjectEmploy in Non-research projects like civil construction, shipbuilding, etc.
15.It was developed in 1957.It was developed in 1958.




  4. References  

1. Content Filter & Authenticity Checking Team, Dream Civil International

(Our team checks every content & detail to maintain quality.)




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