A PERT chart or diagram, short for Program Evaluation (and) Review Technique, is a graphical representation of a project’s tasks and dependencies, used for breaking down and prioritizing work, identifying critical tasks, as well as projecting resource allocations over the course of the project. It is also used to estimate the time it takes to complete various steps in the project. This is best used at the beginning of the project to roughly illustrate some of the high-level obstacles that need to be cleared in order for a project to run as smoothly and efficiently as possible.
Gantt Chart vs PERT Chart
With many commonalities between the two charts, the Gantt vs PERT chart debate is a common talking point when discussing which tool to use for project management. The key things to consider when trying to decide between a PERT vs Gantt chart are:
1. Content and Scale
In terms of content, both the PERT and the Gantt chart are optimized for identifying dependencies in a project. However, the way work is outlined may differ—the key elements of a Gantt chart are the tasks while a PERT chart focuses on events/milestones, with high-level tasks outlined in between.
2. Timing & Focus
A key distinction to make is when a PERT vs Gantt chart is used—a PERT chart is best used at the start of the project for estimating resource allocations based on known dependencies and events/milestones while the Gantt chart is best revisited at the end of every milestone, or as new dependencies and events are identified.
Ultimately, both tools can be used on a single project, with the PERT chart being essential on complex projects that actively involve multiple departments at once. This is because the Gantt chart excels in helping to remove scheduling constraints, while the PERT chart is advantageous for avoiding scheduling constraints entirely.
3. Format
The biggest difference between a PERT and a Gantt chart is in their format. Gantt charts are typically represented by a horizontal bar graph on a timeline—these are used to illustrate task durations. PERT charts, on the other hand, are more free-form. This gives it the advantage of flexibility, as PERT charts can better highlight bottlenecks in the project. Visually, Gantt charts on complex projects show a lot of overlapping lines due to their restrictive format. PERT charts, on the other hand, help overcome this by allowing project managers to freely branch out in all directions as necessary.
Anatomy of a PERT Chart
Pert Chart Example
Understanding the basic parts of a PERT chart before creating our own is important. The above PERT chart example—each numbered square, called a node, represents a key stage, event, or milestone.
Arrows are then used to connect each node to illustrate the sequence in which tasks must be completed. The arrows connecting 1, 2, 4, 6, and 9 show a sequential dependency; these must be accomplished in the exact order, following the direction of the arrows. In some cases, however, a node branches out in two directions. Take a look at nodes 1 and 2, as well as 2 and 3—this tells us that tasks leading up to nodes 2 and 3 can be completed in parallel.
A secondary arrow type, represented by dotted arrows in our example, indicates dependencies that don’t require activity (i.e. time or resources) to unlock. Instead, the preceding events serve as the prerequisite for unlocking a new node.
Estimates for each activity are typically located on the opposite of the arrow for each task.
How to Create a PERT Chart in 4 Steps
1. Define milestones/events and tasks
The first step in the creation of a PERT chart is to identify the different milestones, or stages, of your project. From there, list down the tasks that are required to get from one milestone or another.
2. Identify dependencies
Once you have your events and activities outlined, it’s time to arrange them in chronological order. Which events should happen before the other? Which events can happen simultaneously? Many of the principles in creating a project roadmap apply here.
3. Add nodes and arrows
After identifying dependencies, it’s time to create the actual PERT chart. Begin by creating nodes for each of the events/milestones—it’s best to do it in the order you created previously, so you can illustrate dependencies as you go. Slowly, this will reveal parallel activities as well as the most critical stages in your project. From there, plot your activities between nodes.
4. Estimate work
Now that you have your nodes and arrows, you can begin estimating and attaching these to each activity. This will complete your basic PERT chart and will show the shortest time to complete the critical steps in your project, as well as the total estimate!
Valuable additions beyond the basic elements of your PERT chart include but are not limited to, labeling the resources required/involved in every step of the project, as well as dummy activities.
PERT Chart Template
Workamajig has created an easy PERT chart template just for you so that you can manage your project efficiently.
Advantages and Disadvantages of PERT Charts
Creating and managing a PERT chart comes with many advantages and disadvantages:
Pros
It’s great for visualizing a project’s workflow and complexity
It presents an excellent opportunity to illustrate the distribution of responsibilities between departments
It makes deadlines more predictable since key events are already laid out from the start
PERT charts allow flexibility when visualizing dependencies, making it critical for complex projects
Cons
While PERT charts are optimized for the beginning of a project, this also comes with increased room for error, as the breakdown is mostly subjective, and many changes can happen over the life of a project—this makes the PERT chart highly dependent on a project manager’s skill and experience with scoping and estimating for projects
The level at which work is inspected in a PERT chart makes it less flexible against small changes/roadblocks (this is where the Gantt chart as a companion tool comes in handy)
PERT charts are less intuitive tools for gauging project health
Maintaining a PERT chart is labor-intensive and requires constant review; this is part of why it is best used at the start of the project, and used in tandem with the Gantt chart, as together they cover a wider range of the project lifecycle.
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Start Building Your PERT Chart with Workamajig
A PERT chart is an excellent visual reference to have at the start of your project, so you can prepare for any major obstacles, especially when they concern resource allocations across multiple departments. It also reduces uncertainty by painting an initial picture of how long it will take to accomplish the critical parts of your project.
With Workamajig, the premier marketing management software, you have an all-in-one solution for outlining key events in your project and the activities that allow you to move through each stage of the project as smoothly as possible. Break down tasks, estimate them, and identify dependencies to populate your PERT chart, and instantly convert this into your task management system.
Learn more about Workamajig today, and use it from project intake until project closure for a seamless experience while seeing true project management success.
