Definition and origin of CPM and PERT
El CPM (Critical Path Criterion) and the PERTS (Program Evaluation and Review) are two fundamental techniques in project management that aim to improve the efficiency and effectiveness of planning and execution of tasks. Both methodologies emerged in the context of the industrialization and the development of complex projects, although each has different characteristics and applications.
History of CPM and PERT
CPM was developed in the 1950s by DuPont y Remington-Rand to optimize execution time in the industrial production. On the other hand, PERT was created by the United States Navy for planning projects that require a high degree of uncertainty, such as the development of defense projects.
What is CPM?
El CPM is a technique used to identify critical tasks within a project. It allows the minimum time required to complete the entire project to be determined. The main focus of CPM is that it helps project managers determine which tasks, if delayed, would affect the project completion time.
Elements of CPM
The key elements of the CPM include:
- Activities: They represent the tasks that must be performed.
- Durations: These are the estimated time to complete each activity.
- outbuildings: They show how activities relate to each other.
- Critical route: It is the sequence of activities that determines the total duration of the project.
How to use CPM
The application of the CPM It requires certain steps that are essential for its correct functioning:
Identification of activities
The first stage of CPM is to list all the activities required to complete the project. This is done in the form of a network diagram, where each activity is represented as a node.
Time Estimation
Once the activities have been identified, the duration of each one is estimated. Several factors must be considered, such as available resources, project conditions, and possible unforeseen events.
Establishment of dependency relationships
It is crucial to define how activities are related. Some activities cannot be started until others have been completed. This step is critical to identifying the critical route.
Critical path analysis
With all activities, times, and dependencies clear, the next step is to calculate the critical path. This is the sequence of activities that determines the total project duration. The activities on the critical path are the most critical to meeting deadlines.
Monitoring and control
Once the project is underway, it's necessary to monitor progress and adjust time and resources as needed. This is a vital part of successful project management.
What is PERT?
the PERTS It is a technique aimed at planning and controlling projects where task duration is uncertain. It is particularly useful in research and development projects, where there is a high degree of uncertainty regarding completion times.
Elements of PERT
The essential elements of PERTS include:
- Events: They represent the milestones or start and end points of a task.
- Activities: These are the tasks necessary to advance from one event to another.
- Estimated durations: In PERT, three estimates are used: optimistic, pessimistic, and most likely to give a time range for each activity.
How to Use PERT
Like CPM, PERT follows a series of steps for its effective application:
Identification of activities and events
The first step is to list all the activities and define the key events that will represent the milestones throughout the project.
Estimating times
Unlike CPM, in PERT not only the most likely duration is estimated, but also the optimistic (best case scenario) and pessimistic (worst case) durations. This can be done using the PERT formula:
T = (O + 4M + P) / 6
where T It is the expected time, O It is the optimistic time, M It is the most likely time and P it is the pessimistic time.
Creating the PERT diagram
A diagram is created that connects all events and activities based on their dependencies. This diagram visually illustrates the project flow.
PERT Network Analysis
As in CPM, each path in the diagram is analyzed to identify the critical path. Here, activities with a high degree of variability are of particular interest.
Monitoring and adjustment
Continuous monitoring is essential in PERT. Given the uncertain nature of time in this methodology, it is necessary to be prepared to make adjustments to estimates as the project progresses.
Key differences between CPM and PERT
Below are some key differences between CPM and PERT:
| Appearance | CPM | PERTS |
|---|---|---|
| Our Approach | It focuses on determining times | It focuses on the estimation of probabilities |
| Applications | Projects of construction, manufacture | Projects of research, development |
| duration of activities | Fixed duration | Uncertain durations |
| Diagram | Activity-based network diagram | Event-based network diagram |
Advantages and disadvantages of CPM and PERT
Both techniques have advantages and disadvantages! They are detailed below.
Advantages of CPM
- Clarity in planning: Allows you to view critical activities.
- Time efficiency: Helps reduce delivery times by identifying which tasks are essential.
- Improved resource management: Facilitates the optimal allocation of resources according to the critical path.
Disadvantages of CPM
- Inflexibility: It can be rigid in environments where there are numerous variations.
- Narrow focus: Assumes that durations are predictable, which is not always the case.
Advantages of PERT
- Adaptability: Ideal for projects where there is uncertainty in the duration of the activities.
- Early detection of problems: Facilitates the identification of potential bottlenecks.
Disadvantages of PERT
- Complexity in management: It can be more difficult to manage compared to CPM.
- Extended analysis times: : Requires more time to determine duration estimates.
El CPM and the PERTS are two tools that, although different in approach and application, complement each other in project management. The choice between one and the other depends largely on the nature of the project, the certainty of the activities and the inherent complexity in each. Both allow project managers to have greater control over time, resources and associated risks, which can lead to success in achieving the established objectives.
The implementation of these techniques can result in continuous improvements in the planning and execution processes, optimizing time and resource management in projects of various types. Therefore, both CPM and PERT are fundamental tools in the arsenal of any project manager, providing a structured framework for addressing the complexity and uncertainty inherent in modern projects.
- Adequate training: Ensure the project team is trained in the use of CPM and PERT to maximize their effectiveness.
- Use technological tools: Incorporate specialized software that facilitates the development and analysis of network diagrams.
- Periodic reviews: Conduct regular reviews of activities and estimated times to ensure they remain realistic and timely.
- Combining methodologies: Consider using CPM for parts of the project with clear activities and PERT for those that involve uncertainty.
Both techniques, CPM and PERT, offer different perspectives and approaches that can be tailored to the specific needs of each project. The key is to understand their strengths and weaknesses and select the methodology that best aligns with the project objectives and the nature of the tasks to be executed. With proper planning and effective monitoring, it is possible to increase the likelihood of success in project management, regardless of its complexity or scope.