Estimating Terms (continued)
It is very important that you, as the project manager, estimate your time and share with your team the LOE estimates you have made concerning their work. This work should consist of items such as preparing procedures, meeting attendance, preparing status, obtaining equipment, and so on. Most project managers add 10% to the total effort for administrative items that team members must accomplish in addition to their WBS tasks. If you show the team your estimates for LOE and assure them that time has been added to the estimate for these items, you are in a better position to defend the estimate to management and to explain why 10% is a required amount of time in addition to the WBS items. You can also request help from team members and assure them that they have time to do this task because 10% LOE was built into the schedule.
The difference between effort and duration is that effort relates to the number of labor units required to complete a project activity, whereas duration relates to the number of work periods required to complete it. When you are preparing a schedule, specific resource availability and productivity might affect actual duration.
If the work you are estimating is repeatable and historical data is available to support the productivity of the various groups you are using on your project, then you can use the historical data to project reliable and accurate productivity factors for your current project.