Everything You Need to Know About the Precedence Diagram

by Nash V

Project management is no longer the task it once was. With a greater demand due to growing scale and scope, the job has become more complex. For a project to be successful, there is a need for many people from different sectors, who reside on different continents and function in different time zones, to work together.

Precedence Diagram

While keeping the vendors, developers, marketing strategists, and everyone else in check may seem like a taxing job, there are methods through which task efficiency can be improved to produce the best possible results. Precedence Diagram Method or PDM is one such lifesaver.

What is the Precedence Diagram?

The Precedence Diagram Method is a technique to visually represent the activities that appear in a project schedule. By constructing such a network diagram using boxes or ‘nodes’ that represent each activity, one can identify and visualise the actions that fall under a work stream.

 Each node in the diagram is connected to another one using arrows considering the dependency between them. A dependency is best described as the interrelation between two activities.

Besides, based on the activities coming under the project schedule network, precedence diagrams can dictate the critical paths to the project manager. Critical paths are constructed based on the activities involved, the dependencies between them, and the time taken for each task to reach completion.

It might be tempting to ask why is there a need for such a diagramming method. The answer is simple. Precedence diagrams simplify project management. Especially when a project is intricate and there are chances to miss activities and lose track of deadlines, precedence diagrams help in streamlining the entire ordeal.

How to Create a Precedence Diagram

The primary aim of the precedence diagram is to make a project easier to visualise and execute. To start, the project manager needs to identify the work breakdown structures (WBS). The WBS can be described as what you get when a project is simplified into its skeletal structures or the parts whose total is the project. These need to be arranged in a hierarchical format so that project members know which tasks require immediate attention.

To give a hierarchy to the WBS, the project manager needs to list them and the sequence associated with each task. As you list them, bring together all the actions that are linked. When you look for links between tasks, you will notice absences and repetitions of many actions, fix the links accordingly, and add the actions where required.

When you notice the nature of dependencies between tasks, indicate them using arrows. Once this is completed, you will obtain a network diagram that clearly outlines how you should execute a project. The key to a good precedence diagram is breaking down the project into the best possible forms of deliverable goals and finding the associations between them.

Goals of the Precedence Diagram Method

For a layman, dividing a project into its constituents and then sorting them according to priorities might seem like over complicating the task. However, with the Precedence Diagram Method, professionals find that their projects are seamlessly completed in record time.

The primary goal of precedence diagramming is to give the project managers and team leaders a clear insight on how to proceed with the project. Without the guidance of dependencies and critical paths, too many minds working together can complicate the process. Unnecessary and unavoidable confusions can be avoided, preventing almost all strategic hindrances to the project’s progress.

Another purpose of precedence diagrams is to give all the team members an easy way to visualize the processes involved in the project. The WBS and arrows come together to give a summary of the project at a single glance. This method also allows you to notice the missing activities and relationships of the project.

Finally, the project members have a platform to regularly update the team on their progress and stay on top of deadlines. Since multiple channels of communication with managers of different departments, stakeholders, and vendors can take a toll on the efficient completion of the project, precedence diagrams unite them to reach the targets faster.

What are the Four Precedence Diagramming Dependencies?

Dependencies form a major part of precedence diagrams. Understanding the concept can help you design and interpret these diagrams well. To explain the concept better, let’s look at a fundraising marathon.

1. Start-to-Start Dependency

For a fundraising event to officially start, the organising team needs to settle on the cause they are helping and the target group receiving the funds. Only then can the project truly start with event planning and coordination. This can be described as a Start-to-Start (SS) relationship. The preceding event needs to be started so that the succeeding event can also start.

2. Finish-to-Start Dependency

Finish-to-Start (FS) relationships require the preceding event to finish before the succeeding event can be started. For instance, the organising team needs to dictate the route of the marathon and the rules regarding it so that the marketing team can make the announcement.

3. Finish-to-Finish Dependency

Finish-to-Finish (FF) relationships require the predecessor event to be completed before the succeeding event can be completed. Usually, these events coincide with those that have SS relationships. For a fundraising event to be considered complete, the organising team needs to hand over the donations and clean up after the event. Both these activities happen hand-in-hand.

4. Start-to-Finish Dependency

The last type of dependency is the Start-to-Finish (SF) relationship and it is rarely noted. Here, the preceding event must have started so that the succeeding event is completed. For example, marketing strategies need to be discussed beforehand so that the creative team can work on the content and design for the marketing team to use.

Summing It Up

Precedence diagrams are an efficient way to chart the course of a project’s progress. They help visualise a schedule for the project and allow project managers to reduce confusion while on the job. While designing a precedence diagram, the goal is to identify the WBS as well as the dependencies and critical paths between them. With the help of precedence diagrams, project managers can always stay on top of the game.