Start-to-Finish (SF) Dependency
A Start-to-Finish (SF) dependency is a logical relationship in which a successor activity cannot finish until a predecessor activity has started.
Explanation
Start-to-Finish is the rarest and most counterintuitive of the four PDM dependency types. In an SF relationship, the start of the predecessor activity controls when the successor activity can finish. The successor may already be in progress, but it cannot be completed until the predecessor begins.
The classic example of an SF relationship is a shift changeover. The night shift (successor) cannot finish until the day shift (predecessor) starts. The night shift workers must remain on duty until the day shift workers arrive and begin their work. Another example is a legacy system that must remain operational (successor) until the new replacement system goes live (predecessor starts).
SF dependencies are seldom used in practice and rarely appear in project schedules. However, they are frequently tested on the PMP and CAPM exams because they are the most commonly confused relationship type. Understanding the direction of the dependency (the predecessor's start governs the successor's finish) is essential for exam success.
Key Points
- •Rarest of the four PDM dependency types
- •Successor cannot finish until predecessor starts
- •Classic example: shift changeover or system cutover
- •Frequently tested on PMP/CAPM exams despite rare practical use
Exam Tip
SF is the most commonly tested tricky dependency. Remember: the predecessor STARTING allows the successor to FINISH. Think of a guard who cannot leave until the replacement arrives.
Frequently Asked Questions
Related Topics
Precedence Diagramming Method (PDM)
The Precedence Diagramming Method (PDM) is a technique used to construct a schedule model in which activities are represented by nodes and are graphically linked by logical relationships to show the sequence of activities.
Finish-to-Start (FS) Dependency
A Finish-to-Start (FS) dependency is a logical relationship in which a successor activity cannot start until a predecessor activity has finished.
Sequence Activities
Sequence Activities is the process of identifying and documenting relationships among the project activities.
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