Using WBS summary activity type & top-down estimates in Primavera P6. It is possible in Primavera P6 Enterprise Project Portfolio Management (EPPM) to compare top down estimates beside bottom up estimates. Determining accurate project costs is one of the more challenging efforts in the project management and scheduling process. Top down cost estimates are usually required at the beginning of a project. But as the details of the project take shape a bottom up estimate provides a more accurate and reliable cost estimate.
In Primavera P6 EPPM it is possible to define a top down estimate by insertion of WBS Summary activities. This WBS Summary top down cost estimate can then be compared directly to bottom up estimates.
This article describes how to employ the WBS Summary activity to list top down estimates beside bottom up estimates in Primavera P6 EPPM release 16.1.
WBS Summary Activity
We begin by first creating an activity user defined field (UDF). To create an activity UDF select Administer | Enterprise Data | Activities and Activity UDFs, Figure 1.
Figure 1
The title of this activity UDF is Top Down Estimate and the data type is cost. In the activity table add a column for the Top Down Estimate Activity UDF (Find this in the activity user defined category), Figure 2.
Figure 2
Next add a WBS Summary activity below each WBS element, Figure 3.
Figure 3
The WBS Summary activity in some respects mimics the WBS elements. They both span the length of the WBS elements. And just like WBS elements the WBS Summary activities expand and contract as the associated activities beneath increase and decrease in duration.
The one advantage of the WBS Summary activity over the WBS elements is that you can directly resource and cost load a WBS Summary activity. This is not possible for the WBS elements, which can only rollup the costs of the associated activities below. This makes the combination of the WBS Summary activity and the activity UDF column, specifically our Top Down Estimate column, suitable for listing the projects top down cost estimates.
Simply manually type in a top down estimate for each WBS Summary activity. And compare to the bottom up estimate listed in the Planned Total Cost column, Figure 4.
Figure 4
The planned total cost column accounts for all labor, material, equipment, and expense costs assigned to each activity in the project. These activity costs are then rolled up to the WBS element level. Thus, the planned total cost column provides the more accurate bottom up cost estimate of the project. The top down estimate, however, is helpful for a sanity check comparison to the bottom up estimate.
Summary
It is possible in Primavera P6 EPPM to enter a top down estimate by employing an activity UDF and a WBS Summary activity. This is comparable to the bottom up estimate. The bottom up estimate cost and/or resource loads each activity which rolls up to the WBS element level. Compare this value to the top down estimates, which also roll up to the WBS element level.
Note that in our top down estimate we manually entered the estimated cost of the project management activity. This then rolled up to the total cost of the project in Primavera P6 EPPM along with the WBS Summary activities.