Performing a top-down estimate in P6. Every project comes with budget, and often with a firm fixed price or not to exceed clause to boot. As a scheduler the challenge is it make the work fit the budget.
Primavera P6 Professional supports Top Down Estimating to assist you in making the project fit the budget. You can do this by using weighed activities and the Top Down Estimating feature.
Primavera P6 Professional works great to provide bottom-up estimates of activities and deliverables. Sometimes though you are provided a proposed hours or cost for the entire project, then you must go and compute the impact of that proposed cost on individual deliverables and activities. Well, Primavera P6 Professional also has a top-down estimate feature for distributing the proposed cost of your project among both deliverables and activities.
This article demonstrates how to perform a top-down estimate in P6 Professional.
We have in Figure 1 our demonstration project.
Figure 1
This project currently has no resource assignments. We want to perform a top-down estimate of the entire project. We begin by first displaying the Work Breakdown Structure (WBS) of the project, Figure 2.
Figure 2
In the Columns dialog of the WBS view, we continue by searching and selecting ‘Est Weight’ as a selected option to display, Figure 3.
Figure 3
In Figure 4, we add the ‘Est Weight’ and, additionally, the At Completion Total Cost fields to the WBS view.
Figure 4
Note that the ‘Est Weight’ of piping and thrust block add up to the installation piping system deliverable. All the deliverables; demolition piping, installation piping system, and quality assurance add up to an ‘Est Weight’ of 9.0, but the total ‘Est Weight’ of the project is 10.0. This is done so that we can distribute some of the cost to our high level project management effort.
In the activity table, Figure 5, we include the following columns: ‘Est Weight’, budgeted labor units, budgeted labor cost, and budgeted total cost.
Figure 5
Note that the ‘Est Weight’ of activities add up to the ‘Est Weight’ of the associated deliverables displayed in Figure 4. Looks good! All our weights are distributed among deliverables and activities.
We proceed and insert a lump sum resource into our resource database, Figure 6.
Figure 6
The standard rate of our lump sum resource is $100.00/h. In Figure 7 we see the schedule after assignment of the lump sum resource to all respective activities.
Figure 7
Now we are ready to perform our top-down estimate.
Select Tools | Top Down Estimation…, Figure 8.
Figure 8
In the Top Down Estimation dialog, Figure 9, we select the project top level WBS for WBS.
Figure 9
The resource is lump sum. And we are provided a proposed 600-hour effort for the entire project, which we insert in the estimated units field. Note the estimation method is toggled to prior experience. Click apply. In Figure 10 we see how our 600-hour effort is distributed among activities and associated deliverables.
Figure 10
In Figure 11 we view the WBS, which correlates to the activities table.
Figure 11
This is great, but we want to save our estimate for future reference. Go back into the Top Down Estimation dialog and select the same WBS, resource, and (600-hours) estimated units. This time select save as, Figure 12.
Figure 12
Enter an appropriate name and save, Figure 13.
Figure 13
In Figure 14, estimation history dialog, we confirm that the adjusted units column of ‘Lum Sum 600-hr’ is in fact 600.0h.
Figure 14
Close the estimation history dialog.
Let’s investigate the impact of a 10 percent increase on the estimated units, Figure 15.
Figure 15
In Figure 16 we see the top-down estimate in P6 project with a 10 percent increase on the budgeted labor units.
Figure 16
We again can save this estimate for further review in the top down estimation history.
Summary
You can perform a top-down estimate in P6. Your activity weighting estimates will be more meaningful, if your activity estimated weights add up to the associated deliverable estimated weight. Once an estimate is created you can save it in the top down estimate history for future reference. It is also possible to examine the impact of minor percentage adjustments on the estimated units.