Activity Sequencing Tools & Techniques :
1. Precedence diagramming method
2. Arrow diagramming method
3. Conditional diagramming method
4. Network templates

Precedence Diagramming Method (PDM)

The precedence diagramming method (PDM) is what most project management software programs use today. Precedence diagrams connect activities with arrows that show dependencies between the activities. This method is also called activity on node (AON).

The activity information is written on the nodes with arrows connecting the nodes, or dependent activities. The nodes are shown as rectangles, and you are free to put as much information about the activity on the node as you’d like. The minimum information that should be displayed on the node is the activity name. Sometimes the nodes are displayed with activity name, activity number, start and stop dates, due dates, slack time, and so on. (We’ll cover slack time in a later chapter.) For the exam, remember that the PDM uses only one time estimate to determine duration.


Arrow Diagramming Method (ADM)

The arrow diagramming method (ADM) is visually the opposite of the PDM. The arrow diagramming method places activities on the arrows, which are connected to dependent activities with nodes. This method is also called activity on arrow (AOA). This method is seldom used today. For the record, AOA allows for more than one time estimate to determine duration. The example below shows the AOA method applied to our house-painting example.

Mathematical Analysis
Mathematical analysis includes three commonly known techniques: Critical Path Method (CPM), Graphical Evaluation and Review Technique (GERT), and Program Evaluation and Review Technique (PERT). CPM and PERT are very similar network-planning methods, and in some organizations, CPM and PERT are used synonymously. We’ll examine each of these techniques momentarily. Keep in mind that CPM and PERT are methods to determine schedule durations without regard to resource availability.