What is meant by precedence diagramming method?

It is used for scheduling activities in a project plan. It is a method of constructing a project schedule network diagram using boxes, which are mostly referred to as nodes, to represent activities as well as connects them with arrows that show the dependencies or resources such as; shows the relationship of the tasks to each other, allows for what-if, worst-case, best-case and most likely scenario, critical tasks, noncritical tasks, and slack time.

This usually includes, determining predecessors and defining attributes such as; early start date, late start date, late finish date, early finish date, duration etc.

The precedence diagramming method (which is also known by the three letter anagram PDM) refers to a specific project management technique in which the project management team and or the project management team leader employs a schedule network diagramming technique in order to graphically represent any known and preexisting schedule activities via the use of boxes (which can also be referred to as nodes).

PDM is a tool used by the management for scheduling of the project related activities in a well defined manner in diagrammatic form. This facilitates:

• Ease of communication of the activities to be undertaken by the project team in a well defined and sequential manner.
• Any activity which has been been missed could be identified at the planning stage.
• Helps in identifying the dependencies of the project related activities on each other,
• Project related critical activities are identified; and 
• Helps in creating an effective and doable project schedule. 

Precedence diagraming method(PDM) as compared to Arrow diagraming method(ADM) is currently used by Planning Managers to schedule and control  Projects. In PDM activities are shown in boxes and dependencies between activities are shown by arrow where as in ADM ,activities are shown by arrows .In PDM ,we can have FS,SS,FF,SF types of connections between predecessors and successors .Hence PDM network will be more reliable compared to ADM. 

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.