What is PERT? How is it different from CPM?

PERT stands for Program Evaluation and Review Technique.
A PERT chart is a graphic representation of a project’s schedule, showing the sequence of tasks, which tasks can be performed simultaneously, and the critical path of tasks that must be completed on time in order for the project to meet its completion deadline.
The chart can be constructed with a variety of attributes, such as earliest and latest start dates for each task, earliest and latest finish dates for each task, and slack time between tasks.
A PERT chart can document an entire project or a key phase of a project.
The chart allows a team to avoid unrealistic timetables and schedule expectations, to help identify and shorten tasks that are bottlenecks, and to focus attention on most critical tasks.
CPM stands for Critical Path Method.
CPM is a project management technique that analyzes what activities have the least amount of scheduling flexibility (i.e., are the most mission-critical) and then predicts project duration schedule based on the activities that fall along the "critical path." Activities that lie along the critical path cannot be delayed without delaying the finish time for the entire project.
Projects planned with CPM typically are graphically represented in a diagram showing how each activity is related to the others.

CPM uses "Activity Oriented Network" (useful, when duration of Activity can be estimated) PERT uses "Event Oriented Network" (useful , when duration of Activity is probable.)

PERT vs. CPM (Program Evaluation and Review Technique) are most commonly used methods for project management. There are some similarities and differences between PERT and CPM. PERT can be applied to any field requiring planned, controlled and integrated work efforts to accomplish defined objectives. On the other hand, CPM (Critical Path Method) is the method of project planning consisting of a number of well defined and clearly recognizable activities.

PERT vs. CPM

1. CPM -uses activity oriented network. PERT uses event oriented Network.

 2. CPM-Durations of activity may be estimated with a fair degree of accuracy. PERT- Estimate of time for activities are not so accurate and definite.

3. CPM-It is used extensively in construction projects. PERT- It is used mostly in research and development projects, particularly projects of non-repetitive nature.

4. CPM-Deterministic concept is used. PERT-Probabilistic model concept is used.

5. CPM- can control both time and cost when planning. PERT is basically a tool for planning.

6. In CPM, cost optimization is given prime importance. The time for the completion of the project depends upon cost optimization. The cost is not directly proportioned to time. Thus, cost is the controlling factor.  In PERT, it is assumed that cost varies directly with time. Attention is therefore given to minimize the time so that minimum cost results. Thus in PERT, time is the controlling factor.

PERT is probabilistic nature ie it gives the optimistic, pessimistic and likely time of completion project.
CPM is deterministic ..it gives the minimum time needed to complete the project

PERT : method using to estimate project activities duration by use three types of estimateMost likely: the duration of the schedule activity that happens usually

Optimistic: the activity duration is based on a best-case scenario.

pessimistic: the activity duration is based on a worst-cases cenario.

Calculate the average of the three or use called  PERT

CPM is deterministic ..it gives the minimum time needed to complete the project

and the duration of activity by CPM  = the most likley 

 

PERT : method using to estimate project activities duration by use three types of estimateMost likely: the duration of the schedule activity that happens usually

Optimistic: the activity duration is based on a best-case scenario.

pessimistic: the activity duration is based on a worst-cases cenario.

Calculate the average of the three or use called  PERT

CPM : Critical Path Method  is to Calculating the longest path to finish in project schedule

 

 

 

program evaluation and review technique

Anisuddin,  Usman Ghani , Essam and Mubarak explained it well to understand CPM please go to http://www.oracle.com/us/products/applications/042744.pdf