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Software Project Management under Uncertainties
Event Chain Methodology: Single
Events Properties
A new task duration or cost can be calculated in different ways. The task can be restarted from the moment when an event has occurred. Further, the task can be delayed or duration can be increased/ reduced. For example, duration can be increased by 20%.
The events can be categorized based on relationship between individual tasks (group of tasks) they are assigned to and the tasks (group of task) they are affecting. The event can be assigned to and affect the same task. Alternatively, the event can affect a different task or a group of tasks from the task it was assigned to. For example, a purchase of more powerful hardware will reduce development time for a group tasks. Often a single event can be initiated within a project without any relationship to the particular task. It can affect a single task, a group of tasks, or a complete project. For instance, changes in the project’s budget can affect all tasks from the moment these changes have occurred.
Another property of the event is the chance of its occurrence. For example, there is a 2% chance of the event where the whole project will be canceled due to budgetary constraints. If the cost or duration of the task has been increased or reduced, the event will include additional set of properties. This information includes time or cost additions or time and cost savings. This can be calculated in absolute units (days, dollars, etc.) or as a percentage of the task duration or cost. For example, in event of inconsistent software development requirements, duration of the construction iteration can increase by 30%.
One task can have a group of mutually exclusive events. For instance, there is a 20% chance that duration of a task will be increased by 35%, a 30% chance that duration will increase by 10%, and a 5% chance that task will have to be canceled. Alternatively, the task can be simultaneously affected by some combination of these events. For example, there is a 20% chance that duration and cost can be increased together.
The next property of the event is chronological. This parameter can be deterministic, but in most cases it is probabilistic. For example, the event can occur between the start time and end time of the task minus two days, but will most likely occur two weeks after the task has started. This information can be represented by the triangular statistical distribution.
The time when the event occurs is important. If the event results in the cancellation of the task, to calculate the task duration, it is important to know when it occurred. This information is also crucial when tracking of project performance in order to filter events that could have occurred before the actual date. Finally, in certain cases, it is essential to know when the event has occurred to calculate the new duration and cost.
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