Backward Estimation: Calculate Duration through Task End Date

Backward Estimation is a general estimation method for defining and calculating time length of tasks through a backward analysis. The method is used in cases when end date of a task is set even before the task is defined. For example, such a task can be a component of a larger activity or project that has a definite completion date. Then the task’s end-date equals the project’s completion date.

The advantage of backward estimation is that it lets consider desired outputs and available resources in advance before a task is started. A backward estimate includes some key figures and calculations that help forecast task duration and set an exact start date. The disadvantage is that the method creates a time estimate dependent on high-level timelines and schedules. The method is not applicable if a task has no definite completion date.

Backward estimation can be presented as a process that consists of the following steps:

• Define a task to be estimated
• Check if this task has a preset end-date
• If not, check whether the task belongs to a larger activity or project
• If so, find out completion date of the project
• Regard the task’s end-date as the project’s completion date
• Create a high-level timeline for the task
• Add the end-date to the timeline
• Go backward to the present time to outline the task’s start date
• Calculate a rough duration estimate based upon the task’s end-date and the outlined start date
• Check if goals of the task can be achieved during the roughly estimated period
• If so, approve the outlined start date
• If not, understand what additional time is required
• Determine the task’s duration.

	CentriQS Task Estimation Solution Task estimation is "must-have" of effective time tracking solution. CentriQS offers an easy way to estimate task duration. Users can either enter time required for task execution (if task has no sub-tasks) or break tasks down into subtasks, and then estimated duration of parent task will be automatically calculated as total of subtasks estimates.