What is a Predecessor and Dependency type?

In this article we will review predecessors and dependencies, what they are and the different types.

A Predecessor is a item or task that comes before or is replaced by another. A scope element can have multiple predecessors or successors. Predecessors and successors generally have some form of dependency from a scope element that relates to another scope element. Dependencies represent the order a task must be performed to create the most optimal schedule.

An example being Task #1 that is required to finish before the start of Task #2. This is a Finish to Start dependency and is the most common dependency in project management.

Another example would be Task #1 has to be finished for 4 days before Task #2 starts. This is again a start to finish dependency, but it also includes an offset of 4 days. This is a buffer time to account for any number of situations whether it be travel, prep, approval, review, conclusion etc before another task can start.

Lets look at the available dependency options within the In Scope platform that you can use to create the best schedule for your project.

We'll start by navigating to a schedule within a project by clicking the GANTT tab within your project as highlighted below in the top right. Once in the gantt table go ahead and click a empty predecessor box and click the edit button within the gray navigation bar in the top left as highlighted below.

Once in the edit menu lets select the dependency tab in the blue navigation bar highlighted below. Go ahead and hit the + Add button also highlighted below to add a new dependency and review the options and dependency types available.

As you can see after we hit the +add button we get a new options for name which is the name of the predecessor or successor the task has a relationship to. The type of dependency which we will review below and the offset for the dependency.

Lets review the available options for dependency type:

Finish-Finish In this scenario a task must finish for another task to be able to finish also. An example of this is if you rent something you must finish what you rented for before you can return the rental.

Finish-Start In this scenario a task must finish before another task can start. This is the most common dependency type. An example of this is technical writing must finish before it can start to be published.

Start-Finish In this scenario a task must start before another task can finish. An example of this may be a truck with bricks may need to start to be unloaded before the building team can complete a wall.

Start-Start In this scenario a task must start so that another task can also start. An example of this is a book being written must start so that editing of the writing can also start.

Those are our dependency types. The last thing to select is the offset. In project management this is also called lag or lead, it is the amount of time needed before a task can start in relation to its dependency type. As noted sometimes things need to start before others can finish and sometimes things need to finish before others can start, and so the offset allows us to start and stop tasks at the most optimal times.

As you can see below once you have entered a successor/dependency it will be reflected in the predecessor box as 4FS-4 days, what this represents is this scope element has a finish to start relationship with task #4 and a 4 day offset. This is also shown on the right in the gantt chart following the arrows between tasks.

That's it, you're now ready to create the optimal schedule for your project.