PERT Diagrams

The acronym PERT (Program Evaluation Review Technique) refers to a class of visuals in which processes are depicted as directed acyclic graphs. The activities can be either nodes or arcs of the graph. The methodology was originally developed by the U.S. Navy in the late 1950s as a part of the Polaris submarine missile development program. One major advantage of PERT diagrams over Gantt charts is that they allow the visualization of dependencies between the activities, whereas Gantt charts do not. There are two main types of PERT diagrams, both of which are treated in this chapter: those where the activities are represented as nodes of the graph (activity-on-node, AoN) and those in which they are arcs of the graph (activity-on-arc, AoA).