Task Dependencies in Project Planning
In Project, a relationship between two tasks is known as
a task dependency or task link. Defining the dependencies between tasks helps you
determine which tasks start when, as well as when the project might finish (Biafore, 2010, p. 70).
In any Project there will be an order in which tasks need to be completed - a wall can't be built until it has a foundation, on premise software can't be configured until it is installed.
Wherever there is a dependency between tasks there will always be predecessor tasks and successor tasks.
There are two
types of tasks in dependency relationships: the predecessor and the successor. Successor tasks are
dependent on predecessor tasks. (Daley, 2011, p. 46)
Successor tasks are dependent on predecessor tasks. For example Laying the Foundation is a predecessor task of Building the Wall (you can't build the wall until you have laid the foundation).
Task dependency types set the type of relationship between a successor task and its predecessor(s). For example Building the wall has a finish-to-start dependency with laying the foundation. The foundation must be finished
before building the wall can start
The Four Task Dependency Types in Project Management
There are four task dependency types in Project Management
. The diagram below illustrates each task dependency type.
Finish to Start
This is the most common dependency type, and is the default type set when you link tasks in Microsoft Project. A Finish-to-Start dependency means a task can't start until its predecessors have finished. In other words Task B can't start until Task A has finished.
Start to Start
A task can't start until its predecessors have started. For example, Task B can't start until Task A has started.
Finish to Finish
A task can't finish until its predecessors have finished. For example Task B can't finish until Task A has finished.
Start to Finish
A task can't finish until its predecessor tasks have started. For example Task B can't finish until Task has started.
Task Dependencies - references and further reading
S. Daley. (2011) Microsoft Project 2010 in Depth
. Pearson Education, Inc. p.48.
B. Biafore, (2010) Microsoft Project 2010: The Missing Manual (Missing Manuals)
. p. 70.
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