Precedence diagram method

The precedence diagram method 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 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