Project Evaluation and Review Technique (PERT)

Managing a project requires good planning, proper scheduling, and smooth coordination of tasks. One helpful tool for this is the PERT chart, which stands for Project Evaluation and Review Technique. It is used to estimate how long each task will take and how tasks are linked together. Whether the project is simple or complex, a PERT chart gives a clear view of the workflow and helps spot important tasks that could delay the project. It also improves time estimation, makes teamwork easier, and supports better decisions. In this blog, you will learn what PERT is, its importance in project management, its advantages and limitations, and a step-by-step guide on how to create and manage one effectively.

Table of Contents:

• What is the Project Evaluation and Review Technique (PERT)?
• Importance of PERT in Project Management
• Advantages and Disadvantages of the PERT Chart
• Steps to Create a PERT Chart
• Characteristics of a PERT Chart
• Tools and Software for PERT
• Difference Between PERT and CPM
• Common Mistakes in PERT Chart Creation
• Best Practices for Presenting a PERT Chart to Stakeholders
• Conclusion

What is the Project Evaluation and Review Technique (PERT)?

PERT uses three time estimates for each task: optimistic time, most likely time, and pessimistic time. These estimates help project managers calculate the expected time needed to complete the task. The main goal of PERT is to find the critical path, which is the longest chain of dependent tasks that affect the overall project timeline. This path shows which tasks must be finished on time to keep the project on schedule. By identifying these tasks, project managers can focus on the activities that matter most and take action where delays could affect the entire project.

Importance of PERT in Project Management

There are multiple benefits of using a project evaluation and review technique for planning and scheduling a project:

1. Better time estimation: PERT can help project managers estimate the time for each task with three time estimates:

• Optimistic time (O): It is the least time a task can take.
• Most likely time (M): It is the typical time a task should take.
• Pessimistic time (P): It is the maximum time a task can take.

Using these estimates provides a better project schedule than simply using one time estimate.

2. Helps identify the critical path: The critical path demonstrates the longest string of dependent tasks. If delayed, that string of tasks will delay the whole project. PERT charts help demonstrate this relevant path for the project managers.

3. Better planning and coordination of tasks: The PERT chart will show what tasks must be completed before other tasks can begin. This will help to minimize task confusion and coordination.

4. Minimizes project risks: By visualizing all paths in a project and estimating time wisely, PERT techniques can limit the amount of unforeseen delays in project management. 

5. Improves Resource Management: PERT helps project managers understand which tasks need more attention and more resources.

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Advantages and Disadvantages of the PERT Chart

Like any other project management tool, there are advantages and disadvantages to a PERT chart. A PERT chart improves planning, scheduling, and coordination of tasks, but has some limitations depending on the size of your project and the confidence in the task estimates. Let’s take a look at the major advantages and disadvantages of utilizing a PERT chart.

Advantages of the PERT Chart

Let’s explore the advantages of the PERT chart:

• More Accurate Time Estimates: In each task, PERT assigns three time estimates, which gives a more accurate picture of how much time the task might take.
• Identifies Task Relationships: It shows which tasks must be done first and which can follow, helping the team stay on track.
• Focuses on Key Tasks: PERT will assist the manager in locating the critical path, which means they can focus on the critical tasks that impact the project’s finished timeline.
• Enhances Project Planning: It provides a complete overview of the project, making it easier to plan for each step accurately and mitigating the risk of delays.

Disadvantages of the PERT Chart

Let’s explore the disadvantages of the PERT chart:

• Takes Time to Create: Implementing a detailed PERT chart that includes time estimates and task dependencies can be labor-intensive.
• Estimates May Be Inaccurate: The time estimates in PERT rely on subjective assumptions. It simply takes one incorrect assumption, and the whole schedule is at risk.
• Not Ideal for Simple Projects: PERT charts may be unnecessary for small or straightforward projects, as the level of detail can be excessive and overly complex.
• Can Get Complicated: In extremely large projects with a multitude of tasks, reading and managing the chart can be challenging.

Steps to Create a PERT Chart

Let’s explore the steps required to create a PERT chart:

Step 1: List Activities for the PERT Chart

The first step is to list all the tasks or activities that need to be done in order to complete the project. Every task has to have a clear start point and endpoint. It helps you break down the project into smaller segments that are easier to understand and manage. At this stage, you are not worried about the order of the tasks. You are just concerned with writing down everything that needs to be done in order to complete the project.

Step 2: Identify Activity Dependencies in the PERT Chart

After you have a completed list of tasks, the second step is to identify how the tasks are related. Some tasks can only start after another task is finished. These are called dependent tasks. For example, you cannot begin testing a product until you have built it first. As a result of identifying these relationships among the tasks, you will be able to properly sequence the tasks as they relate to the project. This will provide you with an understanding of the flow of work through the project.

Step 3: Assessing Task Duration by Using PERT

Once you’ve identified the dependencies, you’ll need to estimate how long it will take to do each task. In PERT, this is done using three time estimates:

• Optimistic time (O): The shortest time a task could take
• Most likely time (M): The most probable time the task will take
• Pessimistic time (P): The longest time the task might take if there are delays

Using these values, you can calculate the expected time (TE) for each task with this simple formula:

Expected Time (TE) = (O + 4M + P) / 6

This formula gives more weight to the most likely time and helps you create more realistic and accurate project schedules.

Step 4: Calculate the Critical Path on the PERT Chart

Once you have your time estimates, you can now begin to draw your PERT chart. Connect the tasks according to their dependencies and show the expected time for each. Once you are done, you can identify your critical path. The critical path is the longest path from the start of the project to the end. The critical path must be done on time. If any of the projects on the critical path are late, the entire project will be late. Determining your critical path keeps your project focused on the most critical tasks.

Step 5: Monitor and Control Progress using PERT

Once the PERT chart is created, it serves as an important tool for tracking the performance of the project. You should use it to determine if the work is progressing as planned. If any of the critical path tasks are not completed on time, you’ll know corrective action is necessary. And, as the project moves on, you can also modify the chart, which will help keep you better informed about the schedule and allow for plan changes.

Characteristics of a PERT Chart

Let’s explore the characteristics of the PERT chart:

• Displays Task Sequence Clearly: A PERT chart is used to visually display the order in which tasks need to be completed, as it helps members of the team to understand what is coming next and which task depends on the other task.
• Identifies the Critical Path: The most important feature of the PERT chart is its ability to show the critical path. This is the longest sequence of tasks that must be completed to keep the project on schedule.
• Emphasizes Dependencies: Tasks are shown as connected events, where one usually begins only after another ends. These links clarify how tasks relate to each other.
• Helps with Uncertainty: Since PERT charts explicitly report different time estimates, project managers can utilize them to manage timelines that are uncertain or unpredictable.

Tools and Software for PERT

Let’s explore tools and software for PERT:

1. Microsoft Project: Microsoft Project is one of the leading commercial project planning tools available. It allows for the development of PERT charts, dependencies, and progress tracking. 

2. Lucidchart: If you need a free, simple, and online solution for generating PERT charts, look at Lucidchart. Lucidchart will let you create PERT charts using a simple drag-and-drop approach, and is a helpful tool for teams that would like to create visual project plans. 

3. SmartDraw: SmartDraw provides PERT chart templates. It has an easy-to-use interface for beginner-level users who want to create PERT charts that are clean and organized. 

4. Wrike and Monday.com: Wrike and Monday.com are collaboration tools for team members. It allows the teams to track their project tasks, set due dates, and visualize task dependencies.

5. Excel or Google Sheets: You can also use Excel or Google Sheets to create basic PERT charts. Spreadsheets are flexible and allow you to organize the data manually in your desired arrangement.

Difference Between PERT and CPM

Let’s explore the main differences between Project Evaluation and Review Technique (PERT) and Critical Path Method (CPM):

Common Mistakes in PERT Chart Creation

Let’s explore the common mistakes that people make while creating PERT charts:

• Missing Tasks: Forgetting to include all the necessary tasks can affect the entire plan. Every small component of the project needs to be listed in full detail.
• Wrong Time Estimates: Providing inaccurate or unrealistic time estimates can lead to finding yourself late on the project. Consider time estimates seriously and be willing to draw on experts for guidance, if needed.
• Ignoring Dependencies: If task relationships have not been displayed correctly, the chart can easily provide incorrect information. Always double-check to determine which tasks are dependent upon others.
• Overcomplicating the Chart: Adding too many variables to the chart can result in a confusing chart, rendering it useless. The chart needs to be as simple as possible and only contain the important tasks and timelines.

Best Practices for Presenting a PERT Chart to Stakeholders

Let’s explore the best practices for presenting a Project Evaluation and Review Technique (PERT):

• Utilize Visuals Wisely: When designing a PERT chart, ensure it is clearly organized. Use colors, shapes, and symbols effectively to highlight the critical path and key tasks.
• Clearly Describe The Critical Path: Make sure to clearly define the critical path every time. Stakeholders must know what tasks really affect the success of the project.
• Show Time Estimates: In an easy-to-read table or on the chart, provide the three time estimates for each task. This will show that planning has been done.
• Allow Time For Questions: Allow the stakeholders time to ask questions. They may want to add something to the chart that is good for the overall project.

Conclusion

The PERT chart is a powerful tool that makes project planning, scheduling, and tracking easier, especially for tasks with unclear timelines. It helps estimate how long tasks will take and shows how they depend on each other, leading to more accurate schedules and smarter decisions. It also reduces the risk of delays, makes better use of resources, and highlights the most important tasks to keep the project moving forward. Whether your team is small or your project is large and complex, using a PERT chart can lead to clearer planning and better results.

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Project Evaluation and Review Technique (PERT) – FAQs