PRINCE2 allows for product-based planning with a focus on quality and mapping. Because of this, dependencies must be identified – without this step no control over stage boundaries would be achieved, and realistic planning would be impossible.
What is a Dependency?
A dependency is a link between elements of a product that depend on each other for execution. It’s important for project managers to break projects down into as small milestones/individual products as makes the work manageable and most easily controlled.
Dependencies are especially important in large-scale projects, where later stages can’t be predicted until the earlier parts are complete. The very fact that there are quality checks at the end of each stage means that the initiation of the next stage depends on the success of the one before.
Stage Plans, and especially Team Plans, may not be able to work from the Product Flow Diagram for the purposes of estimation and control. Instead, the managing a stage boundary process is followed.
Types of Dependency
Mandatory and Discretionary Dependencies
An example of a mandatory dependency is set in stone and will not change, e.g. the need for a computer to test new software. A discretionary dependency can change, e.g. product B not to be developed until product A has been tested – this could be changed if there was time pressure later on.
External Dependencies
These are, quite simply, external factors that will affect/effect the progress of the project.
Dependencies in Context – the Product Flow Diagram
The Product Flow Diagram simply shows the order products need to be produced in during the project, and specifies the dependencies from one to the next. It’s important to ensure the same products from the Product Flow Diagram also appear in the Product Breakdown Structure, but not all from the latter need to be included in the former – some of the ‘products’ in the PBS are not products but activities.

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The Product Flow Diagram may be too high-level to estimate and control and the stage and team plan level. By identifying activities and dependencies, you can break the project down much further.
Identifying Dependencies
One method of identifying dependencies is to take a large product that appears in the product flow diagram and breaking it down into the different activities needed to produce that one product. You will now be able to identify the true dependencies of that product/stage, and achieve a higher level of control over the project as a whole.
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