PMO Dependency Types

The 4 Types of Dependencies Your PMO Needs to Know

Knowing what tasks need to follow on from each other helps your project management office (PMO) support projects better. There are four types of dependencies your PMO needs to know about and plan for.

Understanding the dependencies in a project will help when working with the project manager to create the project schedule – you’ll know what order tasks need to go in. It’s rare that a project will have completely linear tasks, so knowing what needs to happen in what order is vital to optimising resources.

To help you support projects when determining dependencies, we’re going to look at:

  • The different triggers for dependencies
  • Mandatory and discretionary dependencies
  • Internal and external dependencies

And we’ll get further into the four different types of dependencies in future articles.

What are the different sequences of dependencies?

When there are several sequences in a task, not everything can be done at the same time. Some will require the same skills and resources as others need things to be completed to be able to start.

It’s important to understand exactly what activities are dependent on each other and factors that may not relate to the project. In general, there are four ways that a task can be dependent on another one:

  1. Finish to start – task one must be finished before task two can start
  2. Finish to finish – task one must be finished before task two can be finished
  3. Start to start – task one must start before task two can start
  4. Start to finish – task one must start before task two can be finished

This is a fundamental way to understand the tasks in a project and is helpful to start to lay out a schedule.

However, there are more detailed paradigms to understand project dependencies which will help you understand what’s important to consider when planning projects.

Mandatory vs discretionary dependencies

This is a way of understanding project dependencies based on what needs to be done versus what should be done. It will help your projects understand what elements can be amended if circumstances change and what can’t be adjusted.

Mandatory dependencies

A mandatory dependency – sometimes also known as hard logic – is an order of tasks that must be completed in that way for reasons such as:

  • Contractual obligations
  • Legal obligations
  • Technical requirements

These dependencies can’t be compromised; you may have agreed with the client that they will get to sign off on work each week, so the sign-off is dependent on the work being done, for example.

When creating a schedule, this type of dependency should be highlighted to ensure it’s not compromised and the project stays on track.

Discretionary dependencies

In contrast to mandatory dependencies, discretionary dependencies don’t have to be completed in a set order, but it’s seen as a standard practice.

Consider a film project – you should have the script completed before casting the actors, but sometimes the cast can be in place before the script is polished.

Discretionary dependencies will be decided based on your business knowledge. Your project manager and subject matter experts will understand what works best when it comes to getting a website live or a prototype produced, for example.

Internal vs external dependencies

Not everything is in the control of your PMO or the project team when getting the project delivered on time and on budget. Knowing who can affect the dependencies on a project will help you understand the level of control you have of the moving parts.

Internal dependencies

An internal dependency is project-specific, i.e. something must happen within the project for something else to happen.

This could be a piece of code that needs to be written before it can be tested in the development environment or that a product design is completed before a piece of machinery can be built.

There is a lot of control over internal dependencies, and good scheduling can keep them on track.

External dependencies

External dependencies require actions to be taken outside of the project to enable a start to get started or finally be delivered.

There are a range of things this could be, such as requiring sign-off on spending from the accounting team to having information delivered by the client before a task can be started. These are things you have little control over, but having strong relationships outside of your PMO can be a great help.

Dependencies your PMO need to know

These four dependencies your PMO needs to know about and work with interact with each other and will affect your project schedule. We’ll be exploring the different types of dependencies and how you can control and plan for them in the next articles in this series.