Activity Level #1
Activity Activity Activity
Activity Activity Activity
Figure 4.1 Hierarchical visualization of the Work Breakdown Structure.
We also use the term work package. A work package is a complete description of how the tasks that make up an activity will actually be done. It includes a description of the what, who, when, and how of the work. We'll describe work packages in more detail later in this chapter.
Breaking down work into a hierarchy of activities, tasks, and work packages is called decomposition. For example, take a look at the top of the WBS in Figure 4.1. Notice that the goal statement from the POS is defined as a Level 0 activity in the WBS. The next level, Level 1, is a decomposition of the Level 0 activity into a set of activities defined as Level 1 activities. These Level 1 activities are major chunks of work. When the work associated with each Level 1 activity is complete, the Level 0 activity is complete. For this example, that means that the project is complete. As a general rule, when an activity at Level n is decomposed into a set of activities at Level n+1 and the work associated with those activities is complete, the activity at Level n, from which they were defined, is complete.
Decomposition is important to the overall project plan because it allows you to estimate the duration of the project, determine the required resources, and schedule the work. The complete decomposition will be developed by using the completeness criteria discussed later in this chapter. By following those criteria, the activities at the lowest levels of decomposition will possess known properties that allow us to meet planning and scheduling needs.
This process of decomposition is analogous to the process we all used in grammar school to prepare a detailed outline of a research paper we were going to write. Despite the teacher's extolling the value of preparing the outline before we wrote the paper, we chose to do it the other way around—by writing the paper first and extracting the outline from it. That won't work in project planning. We have to define the work before we set out to do the work.
Those who have experience in systems development should see the similarity between the hierarchical decomposition and functional decomposition. In principle, there is no difference between a WBS and a functional decomposition of a system. Our approach to generating a WBS departs from the generation of a functional decomposition in that we follow a specific process with a stopping rule for completing the WBS. We are not aware of a similar process being reported for generating the functional decomposition of a system. Veterans of system development might even see some similarity to older techniques like stepwise refinement or pseudo-code. These tools do, in fact, have a great deal in common with the techniques we use to generate the WBS.
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What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.