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Software Project Management under Uncertainties
Event Chain Methodology Overview
The event chains methodology has been proposed to overcome difficulties associated with the estimation of project parameters, as well as to simplify the process of project scheduling with uncertainties for the software development.
According to the traditional project management methodology, the task (activity) is a continuous and uniform process. In reality, the task is affected by external events. These events can transform the task from one state to another. The state can be referred to as a process or part of the process with constant properties.
In most cases, especially for research and development projects such as software development, it is difficult to predict potential events at the stage of project planning and scheduling. Events can occur stochastically during the course of a task. One task can be affected many multiple probabilistic events defined by the event properties: chance of occurrence, probabilistic time of occurrence, and outcome (increase duration or cost, cancel task, assign or remove resource, etc.). These events will be included to the task’s list of events. For example, during the course of development of the particular software feature, it may be discovered that the originally proposed software architecture is not appropriate. This discovery event may cause the cancellation of the feature or even the project. It can also cause an increase in the task duration and cost. The chance of occurrence of this event based on the previous experience of development of similar tasks is 20%. Based on the same historical data, the event should occur during first two weeks of the development.
In addition to probabilistic events, there are also conditional events. A conditional event will occur if some conditions, related to project variables, are met. For example, if the task has reached a deadline, the event “cancel task” can be generated. It is possible to have a combined conditional probabilistic event. For example, if the deadline is reached, there is 20% chance that the task will be canceled.
The events can significantly affect the tasks, a group of tasks, and the whole project. Tasks within a group can have different relationships. It can be a summary task with subtasks. A group may also include tasks with joint resources or other common parameters, which can be affected by the same events. It is important to identify groups of tasks in order to simplify the process of modeling with events.
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