The precedence diagram method (PDM) is a tool for scheduling activities in a project plan. It is a method of constructing a project schedule network diagram that uses boxes, referred to as nodes, to represent activities and connects them with arrows that show the dependencies. It is also called the activity-on-node (AON) method.

• Critical tasks, noncritical tasks, and slack time

• Shows the relationship of the tasks to each other

• Allows for what-if, worst-case, best-case and most likely scenario

Key elements include determining predecessors and defining attributes such as

• early start date

• late start date

• early finish date

• late finish date

• duration

• activity name

• WBS reference

Slack/Float: Determines the duration of activity delay that the project can tolerate before the project comes in late. The difference between the earliest and the latest start time. i.e. Slack = latest start date - earliest start day or Slack = latest finish time - earliest finish time.

Any activities which have a slack of 0, they are on the critical path.

Different Precedence diagram Methods

• Arrow diagramming method

• Project network

• Critical-path method

• Gantt chart

• Program evaluation and review technique

References

Further reading

External links

• Precedence Diagram Method at Better Projects