HKSM
Precedence Diagramming Method (PDM)
A scheduling method that builds a schedule model by showing each activity as a node and connecting them with logical dependencies to illustrate the order in which the work must occur.
Key Points
- Activities are drawn as nodes; arrows show the logical links between them.
- Supports four dependency types: finish-to-start, start-to-start, finish-to-finish, and start-to-finish.
- Allows leads and lags to fine-tune timing between linked activities.
- Forms the basis for network diagrams, critical path analysis, and float calculations.
Example
In a website project, "Code Homepage" cannot start until "Design Homepage" is complete (FS). "Write Test Cases" can begin two days after coding starts (SS with a 2-day lag). "Go Live" cannot finish until "User Training" finishes (FF). Drawing these nodes and links in PDM produces the schedule network and highlights the critical path.
PMP Example Question
Which technique represents activities as nodes and connects them with logical relationships to display execution sequence?
- Arrow Diagramming Method (ADM)
- Critical Chain Method
- Precedence Diagramming Method (PDM)
- Rolling Wave Planning
Correct Answer: C — Precedence Diagramming Method (node-based activity network)
Explanation: PDM depicts activities as nodes with logical links to show sequence. ADM uses arrows to represent activities, not nodes.
