COMPARISON OF THE DIFFERENT BASES

The most common and easiest method of developing the WBS is to use the task, activity, or phase as the basis. The vast majority of elements in most WBSs fit this pattern. By and large, project professionals whose background is scheduling use this as the breakdown basis. It is fair to say that the transition from an activity-oriented WBS to a deliverable-oriented WBS is difficult for those who have developed task-oriented WBSs for a significant amount of time.

One stated advantage for schedule-oriented elements is that the resulting WBS can be used for many projects. Although this feature can be an advantage because the WBS is generic and not specific enough, it is also a disadvantage because the definitive features of the project are not addressed in a clear and highlighted fashion.

Another feature of schedule-oriented WBSs, which sometimes has been perceived as an advantage, is that the WBS is applicable when the project is not fully defined. Unfortunately, this becomes a disadvantage when the project is fully specified but the estimating and scheduling are still dependent on bundled estimates for items such as design, testing, etc.

Ultimately, because projects are carried out when people do things such as develop, draw, print, fix, fabricate, etc., the elements at the lowest level will always be activity-based. However, using the deliverable methodology changes the basis of division from deliverable-oriented to schedule-oriented as low in the WBS as possible.

The second most common basis of developing a WBS is the administrative basis. Project professionals who have a financial or administrative background tend to use disciplines, administrative units, or budget accounts as the basis of WBS breakdown. Although such bases would make tracking of funds very simple and straightforward, they may not significantly help the project management objectives. The bases included in the resource-oriented group—disciplines, administrative units, and financial accounts—should be used as little as possible, because these bases do not refer to the work but rather to the means by which the work is administered and paid for.

The most preferable bases are the deliverable-oriented bases: product, functional system, and physical area. It is very important to make sure that the elements on the first several levels of the WBS, especially those on level one, are deliverable-oriented and not schedule-oriented or resource-oriented. However, this does not mean that activities and costs are not important. On the contrary, a deliverable-oriented WBS that includes activities at the lowest levels results in a more meaningful analysis of the project schedule and project financing. For example, if the testing tasks are late, it would be possible to determine that complexity of testing the item BB has delayed the overall testing results. Similarly, if the costs are significantly below budget, it would be possible to determine that an unexpected reduction in component costs for item CC has caused this unexpected and favorable reduction.