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What Terms are Used in Estimating?

The terms used in estimating are related to the use of project management software. Because of the defaults used in project management software, we have been using these terms in our estimates.

Effort: The hours of labor to do work. Effort is usually expressed as man-hours or people-hours but could be expressed as man-days, man-months, or man-years.
If a task contains four hundred people-hours of effort and there are ten people working on it then it will take forty hours of duration to complete it. If five people are working on the same task, it will have a duration of eighty hours. If the five people working on this task are working on a part-time basis and available 50 percent of the time the duration will be 160 hours.

Duration: Number of time intervals to do work. Duration is usually expressed in working days but could be expressed in any time interval that is convenient. Project management software has been used in a number of nontraditional schedule and resource management applications. One application used project management software to schedule jobs through the central processor of a computer, and the durations were measured in microseconds.

Level of Effort Work: Work done directly for a project but not for a specific activity. One of the things that we want to do in managing our projects is to be able to account for all the things that cost money and take time. This creates a problem for people who work on the project but do not have specific task assignments. Probably the best example of a level of effort person is the project manager. The project manager is managing the entire project but no one task specifically. Since the project manager works on many tasks simultaneously, it is not practical for him to report time against the specific tasks. Time is just charged against the project. Others who provide project level services can also be level of effort workers. The number of people who report to the project as level of effort workers should be kept at a minimum since they may be doing work for specific tasks while not accruing actual cost against a specific task. People who are shared between two or more projects may also be level of effort workers.

Work Time: Calendar time available for work. This term is used to describe the work schedule a person is working. This factor is necessary for project management software to properly allocate and show the availability of people and equipment. Work time is expressed as 09:00 to 05:00, Monday through Friday.

Elapsed Time: Time between start and finish regardless of working or not working. The elapsed time of a task in the project shows the start and finish dates of the task regardless of whether the task is being worked on. A task might start on January 1 and finish on January 10 and have a duration of only five days. The task might be scheduled to be worked on January 1, 2, 3, 9, and 10. January 4 and 5 are Saturday and Sunday, nonworking days, and January 6, 7, and 8 are days when the persons working on the task are transferred to another task. The elapsed time is still ten days.

Availability: The amount of time that a person is available to do work. This can be expressed as a percent of the person’s full-time availability. A person may be available for 50 percent of his or her time.