The Program Evaluation Review Technique or PERT method is useful for managing complex project workflows and estimations. Interested in using the PERT method? Get the details and real examples here.

This article is part of the Project Management Fundamentals Series.

What Is a PERT Chart?

A PERT chart is a network diagram used to depict a project's chronology. The Program Evaluation Review Technique (PERT) enables Project Managers to predict project durations based on job sequence analysis.

Read on to find out more and see six easy steps to make a PERT chart for your project.

Why is PERT important in Project Management?

Project managers use PERT charts to create realistic schedules by coordinating activities and estimating their duration.  

• Each activity is ordered based on inputs and outputs to that step.

• These tasks are documented into a workflow to show how they relate to each other.

• Tasks are then assigned three-time estimates for each activity (optimistic, most likely, and pessimistic).

PERT charts are useful for project planning when the duration of activities is unknown.

When to use PERT in Project Management?

The PERT chart emphasizes the critical route and estimates the time required to complete all project activities. When Project Managers need to know the estimated minimum total elapsed time of a project. And to estimate the minimum and maximum of that total elapsed time. It also ranks all of the tasks in order, which helps to highlight where precursor actions are needed.

Simplify Complex Projects

PERT charts help project managers keep track of major projects. They are useful because they give you an estimate of how much time and resources you will need to complete a project. The PERT chart's structure helps to visualize the complexity of the project and the dependencies between each phase of the process.

Involve Multiple Departments & Subject Matter Experts

A PERT chart may also be used as a project management tool since it gathers data from all departments involved in the project. This aids project managers in determining who is responsible for what and assigning clear duties for those activities. PERT Charts foster clear communication between departments.

Explore the Hypothetical

The ability to generate what-if scenarios is another advantage of utilizing a PERT chart. You can immediately identify what is working and what is not by mapping out the project's tasks, time, and resources. This approach saves time creating multiple waterfall project models (see more about WBS and Waterfall here). PERT charts are important in project management because of their versatility.

How to Make a PERT Chart?

During the planning phase of your project, use a PERT chart. Before we get to our PERT chart example, here are the stages in broad strokes:

1. Begin by establishing project milestones and then breaking them down into smaller tasks.

2. Determine the order in which the tasks should be completed and their interdependencies.

3. Make the PERT diagram — in the section below, we'll show you a PERT chart example.

4. Make a rough estimate of how long each task will take to accomplish.

5. Determine the critical path and any potential slack.

6. You've completed your PERT chart! Keep in mind that the PERT chart is a dynamic document that must be revisited and updated as the project develops.

How to Calculate a PERT Chart?

It's useful to know how to determine a project length using the Program Evaluation and Review Technique before building a PERT chart. Effort Estimates: PERT models use the model of three time predictions for every activity,

Optimistic Time:  (O) The shortest time required to complete a job or activity.

Pessimistic Time: (P) The amount of time required to complete a task or activity under the most optimistic scenario. This is the worst that can happen; anything that has the potential to turn the odds against you will.

Most Likely Time: (M) The most accurate estimate of how long it will take to complete the task or activity, assuming no complications.

Expected Time:  (E) The best estimate of how long the work or activity will take to complete, assuming no difficulties. This is the more realistic time frame.

How to build a PERT Chart?

Let's build a PERT chart together to appreciate its value in project management better. We'll do a project out of developing a website for our PERT chart example. The PERT chart will help us visualize the activities and milestones of our project so that we can easily identify the key route.

In our PERT example, we'll start by identifying all of the project's activities and determining the activities' direct predecessors. We'll make a list of them, which we'll call the activity list. The nodes in our PERT chart are milestones, which are the results of each action.

Then we calculate how long it will take to complete all of the actions required to reach our goals. As shown in our PERT chart example, the time you spend using the PERT chart formula should be added to the arrows. We selected weeks as our time unit but depending on your project. You might use days or months.

We can construct our network diagram after we have a time estimate for each operation. We begin with the first node, which in our case is the "kick off meeting." Then, using arrows, we connect the primary tasks to their appropriate milestone nodes. We repeat the process until we reach the project's last milestone node.

With the chart finished, it's apparent which tasks are essential for completing the project on time. The milestones with darken boxes are used to represent this. Once you've identified the key route, you can use it as a roadmap to keep your project on track.

Which software tools use PERT?

When combined with online project scheduling software, PERT charts become even more powerful. Online tools reduce the project manager's estimation job significantly.  

If you want to know more about online software tools, review the article here.   

The Pros and Cons with PERT

Advantages of the PERT Method:

Managers can use a PERT chart to estimate the time and resources needed to complete a project. 

• This assessment includes the ability to track necessary assets at any point in the manufacturing process throughout the project.

• Data and information from many departments are combined in a PERT study.

• This merging of data promotes departmental accountability and identifies all responsible parties throughout the company.

• It also allows a company to commit to initiatives related to its strategic orientation and enhances communication throughout the project.

• PERT charts may be used to perform what-if scenarios.

• Management may obtain the most effective and beneficial project path by understanding the possibilities regarding the flow of project resources and milestones.

Disadvantages:

Project Teams need to have the skills and time to estimate and order work correctly. Otherwise, the PERT process could derail the Project Management and team.

• The application of a PERT method is extremely subjective.

• Lack of experience can impact outcomes.

• Incorrect data or irrational estimates will lead to plan failures.

Other Considerations when using the PERT Method:

• PERT charts are deadline-driven and may not adequately represent a project's financial status.

• The PERT chart is efficient, but it takes time and resources to set up and store data.

• For a PERT chart to be useful, it must be reviewed regularly and tested against current projections, actual performance, and future estimates.

I hope you found this information helpful. Ready to use PERT on your next Project? Please let me know in the comments below. And let me know what other Project Fundamental you’d like to hear more about.

Thanks!