Reviewing Work Breakdown Structures 143

Using WBS Milestones

In the initial stages of project planning, the project manager, and other individuals responsible for establishing project processes, need to decide how the module will calculate earned value, percent complete, resource use, and financial data.

You can add an unlimited number of WBS milestones, which can also be used to calculate earned value. Milestones are assigned at the WBS level, and each milestone is given a weight that indicates its importance to the project schedule. When you mark a WBS milestone as complete, the module uses its weight to calculate the performance percent complete of all activities included in the WBS level. That is, the performance percent complete is applied to all activities under that WBS level and then rolled back up to the WBS.

For example, suppose a particular level of the WBS includes 10 activities, and actual finish dates have been entered for 5 of these activities. The same WBS level is also assigned four WBS milestones having equal weights, but only one of these milestones is marked as complete. The module uses the completed WBS milestone to calculate the WBS level’s performance percent complete as 25, even though half the activities included in the WBS level are finished.

You may want to use WBS milestones when higher-level task increments comprise a body of activities and you want to control the activities at the WBS level. For example, to control the design of a new product, you might assign WBS milestones to the major steps required to complete the design—such as drafting the requirements, writing the design specifications, and so on. Each of these milestones would contain the detailed activities required to complete it.

The first milestone is complete, and the corresponding performance percent complete, relative to the other WBS milestones, is shown.

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144 Part 2: Structuring Projects

If a WBS element has no activities beneath it, and you mark milestones as complete, the performance percent complete will remain zero. To calculate performance percent complete, add a dummy activity to the WBS element.

Add WBS milestones Use the WBS Milestones tab to add an unlimited number of WBS milestones to a WBS element. Click Add, then type a name for the milestone and assign a weight for calculating performance percent complete for all activities in the WBS element.

When you mark the checkbox for a milestone, the module calculates the performance percent complete for the WBS element based on the milestone’s weight value in combination with the other milestones listed.

How Weights Affect Percent Complete

If all weighted milestones for a WBS element have a value of 1.0 and you have a total of four milestones, marking one as Completed would indicate that the WBS element is twenty-five percent complete. If this same milestone had a weight of 9.0, and the other three had 1.0 weights, marking it Completed would indicate that the WBS element is seventyfive percent complete. The module uses the following formula to calculate percent complete from weighted milestones:

Actual Weight of Completed Milestones / Total Possible Weight of All Milestones

Applying this formula to the previous example, the completed milestone has a weight of 9.0, and is divided by the total weight of all milestones (12.0), to equal seventy-five percent complete.

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