| Solution ID: prim17595 |
| What is "Top Down Estimation" |
| Status: Reviewed |
| Version(s): 4.0, 4.1, 5.0, 6.0, 6.1, 6.2, 6.2.1 |
| Problem: | What is “Top Down Estimation” |
| Fix: | Top Down Estimation is a convenient way to set up the initial planned effort for activities in a project plan and to calculate a ballpark figure for cost and time. The Top-Down Estimation feature enables you to apply labor, nonlabor, and material resource units to WBS elements and activities in a top-down manner using estimation weights. You can limit the scope of your estimate according to work breakdown structure (WBS) element and resource. After you develop a top-down estimate, save the estimate for later reference, or apply the estimate to the project. If you apply an estimate, Project Manager updates budgeted labor/nonlabor units for all activities and activity resource assignments that fall within the estimation scope you specify. Top-down estimations do not affect project expenses. To perform top-down estimation, you must first assign estimation weights to WBS elements and activities. These estimation weights are used to determine how units are apportioned among WBS elements. You can assign estimation weights directly in Project Manager or import them from Project Manager using Project Architect. When performing a top-down estimation, you first determine the total number of labor or nonlabor resource units you want to apply. You can determine this number using either prior experience on similar projects, or you can use the Function Point option, if you are estimating an information technology project. Note
Under certain circumstances, Top Down Estimation will affect an activity’s Original Duration. These circumstances are if:
Then the changes that the Top Down Estimation feature makes to the Budgeted Labour Units will adjust the activity’s Original Duration. (If the Resource Assignment’s Drive Activity Dates option is switched off, then the Original Duration of the Activity will be unaffected and only the Resource Assignment’s duration will be affected.) These changes will be made according to the duration type of the activity. Further information about Duration Types and how they affect the Duration, Units/Time and Units calculations when certain aspects of an activity change can be found on the following knowledgebase solution: Solution 20011024135754 ”How the Duration Type affects Duration, Units/Time and Units calculations” Please note that the changes made by the Top Down Estimation feature cannot be reversed using the Undo feature of the software (Undo is available in version 5.0). |