I have written this post to provide a complete explanation of Project Dependencies. You will find the definition, meaning and examples of project management dependencies in this post. You will also see small diagrams that will help help you in understanding the concept easily.
This is the third post in a series to describe generally confused project management terms. In the other two posts I explained Project Assumptions and Project Constraints. After reading all three posts, you would know the difference between project dependencies, assumptions and constraints.
Definition & Meaning – What is Project Dependency?
A project dependency is better characterized as schedule or task dependency. It simply means that one task or activity is dependent on another one. Sometime these are (incorrectly) referred to inter-dependencies. Inter-dependencies are between two different projects.
A dependency between two activities, or between an activity and a milestone.
You can also look at Max Wideman’s Glossary for other definitions.
Project Dependencies Examples
Let us consider two activities A and B. For our example, B is dependent on A through FS relationship without and lead or lag. It simply means that B would start as soon as A finishes. We can say that B is dependent on A.
I have used Finish to Start relationship in the above example without any lead or lag. But dependencies can be expressed for other project relationships as well – Finish to Finish, Start to Start and Start to Finish.
The above example can be depicted in one of the following ways.
Bar Chart Representation
Bar charts are popularly known as Gantt Charts.
Project Network Diagram Representation
This figure 2 shows the same dependency using a Network Diagram.
B(S) = A(F)
The above equation suggests that start of B is equals to finish of A.
Project Management Dependencies Example – A Real Scenario
Let’s understand the concept through the same example that I used in Project Assumptions and Project Constraints posts.
Situation – PM requires an Approval of 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 cannot do anything but wait if the 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).
Difference Between Project Dependencies, Assumptions and Constraints
Dependencies vs Assumptions
Project Assumption can be defined as a statement that is generally considered to be a true without any proof or evidence. It is one of the major factors in planning process. In the above example, dependency and assumption have no real relationship.
Project Dependencies & Assumptions are very different from each other. An assumption may be identified because of a task dependency. Or additional dependencies could be determined due to identified assumptions.
Dependencies vs Constraints
A constraint simply means limitation. A project could have Constraints due to many factors – task dependency is just one of them. In the above example, the Project Team was “Constrained” due to Customer’s Activity (Design Approval). They could not do anything till customer’s approval (limitation).
In many other cases the Project Constraints may not come because of an Activity. For example the Project Constraints could be due to unavailability of resources, shortage of budget, external environment etc. None of these is a separate activity of the project.
Project Dependencies are considered solely between two Activities.
- They are also called Schedule/Task Dependencies.
- They could be either Mandatory or Discretionary. At the same time, they could also be External or Internal.
- They need not be separately documented. They should, rather, be depicted in the project schedule through Bar Charts and Project Network Diagrams.
- Identification/Determination of Project Dependencies is important part of scheduling.
- Discovery of new project activities or dependencies can lead to modification of the project schedule.
Over To You
How do you use the term ‘Project Dependency’ in your projects? Do you use Assumptions, Constraints and Dependencies interchangeably? Please leave a comment below.