What are Project Dependencies?

Do you know what the difference between Project Dependencies, Assumptions and Constraints is?

Project Dependencies

This is the third post in a series to describe Project Dependencies, Assumptions and Constraints. I have already written two posts to explain Project Assumptions and Project Constraints. This post is written to describe Project Dependencies. After reading all three posts, you should be able to understand the finer points about these terms and recognize the difference. These three terms have immense utility in Project Management. They should be used appropriately.

What is a Project Dependency?

Project Dependencies are better characterized as Schedule Dependencies. A Project Dependency simply means that one activity is dependent on another activity. For example, consider two related activities A and B. If Start of B is dependent of Finish of A. It simply means that B cannot start until A finishes. The Dependencies could be depicted using one of the following diagrams.

You can also look at Max Wideman’s Glossary for the definition of Project Dependencies.

Example of Project Dependency using a Bar Chart

project dependencies

Figure 1 – Click to Enlarge


Example of Project Dependency using a Project Network Diagram

project dependencies

Figure 2 – Click to Enlarge


Figure 1 shows the Project Dependency using a Bar chart which is popularly known as Gantt Chart. Figure 2 shows the same Project Dependency using a Network Diagram.

I have used Finish to Start relationship in the above example on Project Dependency. The Dependencies are to applicable on other Project Relationships also – Finish to Finish, Start to Start and Start to Finish.

Let’s understand the concept of Project Dependencies through the same example that I used in Project Assumptions and Project Constraints post.

Situation – PM requires an Approval on Design Artifacts from the Customer during the course of the project. Project cannot move ahead without this Approval.

PM may “Assume” that the Approval may come within 2 weeks. But until the Approval comes, Project Team is “Constrained” to wait. The team will have to wait even if Design Approval is delayed.

Project Dependency – The Activities of Project Team will start only after Customer’s Activity (Design Approval) is complete. The next Activity of Project Team is “Dependent” on Customer’s Activity (Design Approval).

A Few Key Points

  • Project Dependencies are also called Schedule Dependencies as they are determined between 2 Project Activities.
  • Project Dependencies could be Mandatory or Discretionary.
  • Project Dependencies could be External or Internal.
  • Identification/Determination of Project Dependencies is important part of Project Scheduling.
  • Discovery of new Project Activities or Dependencies can lead to modification of Project Schedule.
  • Project Dependencies need not be separately Documented. They should, rather, be depicted in Project Schedule through Bar Charts or Project Network Diagrams.

But, I still cannot fully understand how Project Constraints are different from Project Dependencies? They look the same to me.

A Project could have Constraints due to many factors. In the above example, the Project Team was “Constrained” due to Customer’s Activity (Design Approval). In other cases the Project Constraints may not come because of an Activity. For example the Project Constraints could come because of unavailability of resources, shortage of budget, Environment etc. Project Team may not define any separate activities for these Project Constraints.

Project Dependencies are considered solely between two Activities.

You should also refer to my other article on 4 Types of Project Dependencies.
You should also refer to my other articles on difference between similar Project Management Terms.
Praveen Malik, PMP is a certified Project Management Professional (PMP®) with a rich 20+ years of experience. He is a leading Project Management Instructor and Consultant. He regularly conducts Project Management workshops in India & abroad.

One thought on “What are Project Dependencies?

  1. Thank you for posting this explanation Praveen. You really break the information down to easily understood terms and I like the examples. As a CAPM, I am still learning these differences and your post help me greatly.

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