INPUTS VERSUS OUTPUTS—RESOURCES VERSUS DELIVERABLES
It is important to understand the differences between the inputs to the project and the output products. The concept of an output- or deliverable-oriented structure can sometimes be difficult to grasp.
For years, planning has been performed in terms of the organizations and resources doing the work, that is, the “inputs.” The use of a WBS requires a different perspective—a focus on the output. The output is what is going to be produced: the product, service, or result. Project inputs include the labor and cost resources necessary to perform the work. They are essential, of course, but approaching project planning from this perspective risks missing major elements of work. Typical project inputs include cost elements such as those shown in Figure 2-16.
FIGURE 2-16 Typical Project Inputs
These items are not ignored in developing a WBS or in project planning; the assignment of inputs to individual activities is performed. Most current project management software programs have resource tables that contain lists and costs of project inputs. Items are selected from the resource table and assigned to individual activities for cost estimating and resource planning.
In addition, pricing proposals are often required to be structured by categories similar to these and to include overhead rates. However, the primary purpose of the WBS concept is to develop a framework for planning that ensures all the work is identified. After this is accomplished, the assignment of resources and cost elements can be accomplished at the work package or activity level, and the work can be scheduled and sorted by input or organization as necessary to communicate requirements for work performance.
Deliverables versus Intermediate Outputs
Project deliverables, as defined previously, include any measurable, tangible, verifiable outcome of a project. They can be a product, a service, or a result. There may be hundreds of deliverables on a large project, such as the Ship System of Figure 1-12, especially where many data items are required to support the product. Each one of these, and the related work, needs to be identified and included in the WBS.
Deliverables need not only represent the product handed to the customer at the end of the project. Usually, intermediate outputs must be developed. Some examples may further clarify what is meant by the intermediate deliverable or intermediate output.
For the sample project of building a garage, the obvious output or deliverable is a completed garage. The WBS for the garage is shown in Figure 2-17 in outline format. The Level 2 elements, the first level of decomposition, are shown in bold.
There are many intermediate outputs. One category of output includes the items that the Project Management Office must produce to support the project. This includes intermediate outputs such as securing financing and developing and preparing subcontracts and construction plans. A completed piece of paper shows when each activity is finished. Another category of intermediate outputs is the county permits that must be acquired, and each inspection results in a certificate from the inspector or a signed inspection sheet. Actually all the Level 2 items under “Project Management” represent work packages with intermediate outputs.
A sample of the first two levels of another WBS is shown in Figure 2-18.
FIGURE 2-18 Book Project Level 2 WBS
Four Level 2 outputs are identified. One is “Project Management,” which includes the intermediate outputs of such things as meetings, reports, and reviews. A second category, a cross-cutting analytical category, is “Research,” which is necessary for the writing of the various chapters. The third category, “Writing,” includes the book contents. “Research” is not an input resource, but a category of intermediate work output that is delivered to the “Writing” work area. The output of the Writing element is not a completed book but a set of completed chapters and items such as the table of contents and the cover. The fourth output is “Publishing,” which includes the reviews of completed drafts of the book and the actual printing of proofs and the final copies. See Chapter 10 for the complete Book Project WBS.
Neither of these WBSs includes labor or cost elements. As mentioned previously, the labor and cost items are identified with the activities and are input items identified at the work package or activity level.