Event chain diagrams are visualizations that show the relationships between events and tasks and how the events affect each other. Event chain diagrams are introduced as a part of event chain methodology. Event chain methodology is an uncertainty modeling and schedule network analysis technique that is focused on identifying and managing events and event chains that affect project schedules. Event chain methodology is the next advance beyond critical path method and critical chain project management.

Rules

Event chain diagrams are presented on the Gantt chart according to the specification. This specification is a set of rules, which can be understood by anybody using this diagram.

For single events

For event chains

Often event chain diagrams can become very complex. In these cases, some details of the diagram do not need to be shown.

Optional rules

The central purpose of event chain diagrams is not to show all possible individual events. Rather, event chain diagrams can be used to understand the relationship between events. Therefore, it is recommended the event chain diagrams be used only for the most significant events during the event identification and analysis stage. Event chain diagrams can be used as part of the risk identification process, particularly during brainstorming meetings. Members of project teams can draw arrows between associated with activities on the Gantt chart. Event chain diagrams can be used together with other diagramming tools. The simplest way to represent these chains is to depict them as arrows associated with certain tasks or time intervals on the Gantt chart. Different events and event chains can be displayed using different colors. Events can be global (for all tasks in the project) and local (for a particular task). By using event chain diagrams to visualize events and event chains, the modeling and analysis of risks and uncertainties can be significantly simplified.

State Tables

Another tool that can be used to simplify the definition of events is a state table. Columns in the state table represent events; rows represent the states of an activity. Information for each event in each state includes four properties of event subscription: probability, moment of event, excited state, and impact of the event. State tables help to depict an activity's subscription to the events: if a cell is empty the state is not subscribed to the event. The ground state of the activity is subscribed to two events: “architectural changes” and “development tools issue”. If either of these events occurs, they transform the activity to a new excited state called “refactoring”. “Refactoring” is subscribed to another event: “minor requirement change”. Two previous events are not subscribed to the refactoring state and therefore cannot reoccur while the activity is in this state.