How to Create a PERT Chart

ProjectManager.com

Want to know what a PERT chart is and how it can help you manage your project? Jennifer Bridges, PMP, shows you.

Here’s a shot of the whiteboard for your reference!

PERT chart basics

In Review – How to Create a PERT Chart

Jennifer noted that PERT is an acronym that stands for Program Evaluation and Review Technique. It’s a statistical tool that can be very useful when working on a project, as it analyzes and represents the project’s tasks

History of PERT Charts

PERT in project management has been around for a while, but it in fact was developed in the U.S. Navy. In 1957, its Special Projects Office created the PERT chart to assist in its Polaris nuclear submarine project.

Since then, it’s found a home in all manner of industries, even the 1968 Winter Olympics in Grenoble.

PERT in critical path method came about at roughly the same time, growing from the scientific management founded by Frederick Taylor, also called Taylorism, which was later refined by Henry Ford. But the use of the term critical path comes from DuPont, which developed the method also in the late 1950s.

Creating a PERT Chart

When creating a PERT chart tasks, or activities, are represented as arrows on the diagram. The dates of project milestones are represented as nodes, or circles.

A PERT event is a point that marks the start of completion of one or more activities.

There are also predecessor events, which occur immediately before some even, and a successor event, which naturally occurs afterwards.

PERT has four definitions for the time required to accomplish an activity.

  1. Optimistic Time, which is the least amount of time to accomplish a task or activity
  2. Pessimistic Time, which is the maximum amount of time to accomplish a task or activity
  3. Most Likely Time, which is the best estimate of how long it will take to accomplish the task or activity, assuming there are no problems
  4. Expected Time, which is the best estimate of how long it will take to accomplish the task or activity, assuming there will be problems

Terms Related to Using a PERT Chart

  • Slack: The amount of time a task can be delayed without causing an overall delay to the project or other tasks.
  • Critical Path: Charts the longest path from beginning to the end of a task or event.
  • Critical Path Activity: An activity with no slack.
  • Lead Time: How much time you should complete a task or activity without impacting the following ones.
  • Lag Time: The earliest time in which to a task can follow another.
  • Fast Tracking: Working tasks or activities at the same time.
  • Crashing Critical Path: Shortening the time of a task.

Steps to Implementing a PERT Chart

  1. Determine the tasks required to complete the project, the order in which they must be done and their duration.
  2. Create a network diagram with arrows representing activities and nodes being milestones.
  3. What is the critical path and possible slack?

Pro-Tip: PERT charts can be used prior to executing the project. They’re a great way to help you estimate simply and more accurately. Estimates can be overly optimistic or pessimistic, but using a PERT chart will find the most realistic estimate.

Thanks for watching!

Transcription:

Today, we’re talking about how to create a Pert Chart. So Pert stands for Program Evaluation Review Technique. It’s been around for some time, it was actually created in the ’50s by the U.S. Navy to manage the Polaris Submarine Missile Project.

Around the same time, the private sector created a similar technique called the Critical Path technique that you probably heard of as well on the project management arena. But they’re very similar, they both helped to plan, schedule, and control projects, and they both use a precedence diagram in their technique.

So there are two rules to create a Pert Chart. The first one is the task, or the activities are represented in the diagram as arrows, which I’ll show you in just a moment. and you may have heard this in the project management arena, it’s called the activity-on-arrow diagrams because, in the graphical depiction, or the diagram, the activity is literally sitting on the arrow.

The second rule is that the milestone dates are represented as nodes, and again, I’ll show you both. But if you think about it, we do this all the time not only in our daily lives but in our project management life.

So if we take one activity and show it on a Pert Chart, we have collect project data is the activity, so it’s sitting on the arrow. And these are the nodes. The estimate of time to do this is one day, so we have to collect the project data before we can submit the project data. So this is a simple one activity depiction.

So if we expand this out to an example with multiple activities, we can see that the circles are the nodes, those are the milestone dates, and then the arrows are the activities.

So the numbers sitting on top of the arrows, that’s the estimate, a duration of time it takes to complete that activity. And then also if you look at these, you can see that when this milestone is done it can initiate multiple activities. In this case, activity, these two activities are initiated when that one is complete.

So that’s why we reference a precedence diagram, so precedence diagram means that something has to proceed that activity being done. But as you can see, it can become quite complex, and some people can still do this manually, but it helps tremendously using a tool.

So if you need a tool to help you with your Pert Chart, then sign up for our software now at projectmanager.com.

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