What Is a Program Evaluation Review Technique (PERT) Chart?

What Is a Program Evaluation Review Technique (PERT) Chart?

Let me tell you directly: a program evaluation review technique (PERT) chart is a graphical representation of a project's timeline that displays all the individual tasks needed to complete the project. It's a project management tool that lets you map out the timeline and break down individual tasks. With a PERT chart, you can communicate project instructions clearly and set schedules and timelines without unnecessary fluff.

Key Takeaways

Here's what you need to know: a PERT chart uses circles or rectangles, which we call nodes, to represent project events or milestones. These nodes connect via vectors or lines that show various tasks and their dependencies. This setup allows you, as a manager, to evaluate the time and resources required for the project. You can create one using software like Microsoft Excel. Remember, PERT charts originated in the 1950s with the U.S. Navy's Special Projects Office for the Polaris nuclear submarine project.

How Program Evaluation Review Technique (PERT) Charts Work

A PERT chart relies on nodes—those circles or rectangles—to mark project events or milestones. These connect with vectors, which are lines representing tasks. Dependent tasks mean one must finish before the next starts; for instance, if an arrow goes from task 1 to task 2, you complete task 1 first. Parallel tasks happen at the same stage but on different lines—they're independent and run simultaneously.

As a project manager, you create a PERT chart to analyze all tasks and estimate the time each requires. This lets you figure out the minimum time to complete the whole project. It also aids in developing a budget and determining necessary resources. Importantly, a PERT chart highlights the critical path, which is the longest sequence from start to finish, setting the minimum project duration.

How to Interpret a PERT Chart

Think of a PERT chart as a visual map of events that must happen over a project's life. Arrows show the flow and sequence. Dotted lines indicate dummy activities on other paths. Each vector has numbers and time allotments. Key terms include optimistic time as the shortest duration, pessimistic time as the longest possible, most likely time as a reasonable best-case estimate, and expected time that factors in problems.

PERT charts resemble critical path analysis, another tool for charting tasks. The difference is PERT uses various time frames and probabilities for estimates.

Advantages and Disadvantages of PERT Charts

As a project management tool, PERT charts have clear advantages and disadvantages. On the positive side, they let you evaluate time and resources needed, track assets at any stage, and incorporate data from multiple departments, which boosts responsibility and communication. They support what-if analyses for efficient paths and help commit to strategically relevant projects.

On the downside, the data can be subjective, leading to unreliable estimates for cost or time. They focus on deadlines but might not cover financial aspects fully. Creating and updating them is labor-intensive, requiring continual review to stay valuable.

PERT Chart vs. Gantt Chart

The Gantt chart predates PERT, created by Henry Gantt in the early 20th century, and it's still widely used. Like PERT, it's a graphical timeline, shown as a horizontal bar chart with start and end dates for elements and their interdependencies. Both define key tasks, estimate time, money, and resources, and monitor progress.

Early Gantt charts didn't show dependencies, but later versions do. PERT is often preferred for identifying dependencies, sometimes used in planning while Gantt monitors execution.

Example of PERT Chart

PERT charts started with the U.S. Navy in the 1950s for the Polaris missile project. Managers used them to evaluate progress, validate schedules, and estimate changes. This success led to their use across industries.

What Are the Main Components of a PERT Chart?

A PERT chart shows key deliverables, time and resources per task, and responsible parties. Arrows indicate order and dependencies.

How Can I Create a PERT Chart?

You can use Microsoft Excel or software like Lucidchart with templates.

Why Would I Use a PERT Chart Instead of a Gantt Chart?

PERT requires thinking through optimistic, pessimistic, and most likely timelines, defining ideals and barriers from the start.

The Bottom Line

Project management is challenging, but tools like PERT charts help. They visually map timelines, highlight tasks, and lay out instructions and schedules. Create them with software or Excel.