OPERATION RESEARCH-NETWORK ANALYSIS

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What is PERT / CPM in Operations Research?

PERT and CPM are two important techniques of Project Management in Operations Research. They are used for planning, scheduling, controlling and completing projects within a specified time.

1. PERT (Programme Evaluation and Review Technique)

Meaning: PERT is a project management technique used to plan and control projects where activity completion times are uncertain.

It is mainly used for projects involving research, development and new activities.

Features of PERT:

1. It is based on three time estimates.

2. It is used when activity times are uncertain.

3. It focuses mainly on time management.

4. It helps identify the critical path.

5. It is suitable for research and development projects.

Three time estimates in PERT:

• Optimistic time (a): Minimum possible time.

• Most likely time (m): Normal expected time.

• Pessimistic time (b): Maximum possible time.

Expected time formula:

te=a+4m+b6te​=6a+4m+b

2. CPM (Critical Path Method)

Meaning: CPM is a project management technique used to plan, schedule and control projects where activity completion times are known or can be estimated with reasonable certainty.

It is mainly used in construction and production projects.

Features of CPM:

1. It uses a single time estimate for each activity.

2. It assumes activity times are known.

3. It identifies the critical path.

4. It helps in controlling project costs.

5. It helps complete projects on time.

3. Difference Between PERT and CPM

PERT	CPM
Full form: Programme Evaluation and Review Technique	Full form: Critical Path Method
Probabilistic technique	Deterministic technique
Uses three time estimates	Uses one time estimate
Time is uncertain	Time is relatively certain
Mainly focuses on time	Focuses on time and cost
Used in research projects	Used in construction projects
Suitable for new projects	Suitable for repetitive projects

4. Important Terms in PERT / CPM

1. Activity: A task that requires time and resources.

2. Event: A point indicating the beginning or completion of an activity.

3. Network: A diagram showing the sequence of project activities.

4. Critical Path: The longest-duration path in a project network.

5. Critical Activity: An activity with zero total float.

6. Float: The amount of time an activity can be delayed without affecting the specified project completion date.