ESTIMATED RESOURCES IMMEDIATE PREDECESSOR TASKS ESTIMATED TIME DURATION(S) TASKS ASSIGNED TO FIGURE 6.4 A form to assist hierarchical planning. The Work Breakdown Structure Using this hierarchical planning process results in a work breakdown structure known as a WBS. The WBS is the main tool for managing the project scope as described in PMBOK®. The WBS is not one thing. It can take a wide variety of forms that, in turn, serve a wide variety of purposes. In many ways, the WBS is a simplified form of the project plan focused on the actual tasks of the project. It often shows the organizational elements associated with a project subdivided into hierarchical units of tasks, subtasks, work packages, etc. Figure 6.5 is such a WBS for a conference. The Food group in the Facilities staff has responsibility for meals and drinks, including coffee breaks and water pitchers in the conference rooms. Five different food functions are shown, each presumably broken down into more detailed tasks. In this case, the account numbers for each task are shown so that proper charges can be assigned for each piece of work done on the project. Professor Andrew Vazsonyi has called this type of diagram a Gozinto chart, after the famous Italian mathematician Prof. Zepartzat Gozinto (of Vazsonyi's invention). Readers will recognize the parallel to the basic organizational chart depicting the formal structure of an organization, or the Bill of Materials in a Materials Requirements Planning (MRP) system. Another form of the WBS is an outline with the top organizational (Level 1) tasks on the left and successive levels appropriately indented. Most current project management software will generate a WBS on command. Microsoft's Project®, for example, links the indented activity levels with a Gantt chart that visually shows the activity durations at any level. In general, the WBS is an important document and can be tailored for use in a number of different ways. It may illustrate how each piece of the project contributes to the whole in terms of performance, responsibility, budget, and schedule. It may, if the PM wishes, list the vendors or subcontractors associated with specific tasks. It may be used to document that all parties have signed off on their various commitments to the project. It may note detailed specifications for any work package, establish account numbers, specify hardware/ software to be used, and identify resource needs. It may serve as the basis for making cost estimates or estimates of task duration. Largely, the WBS is a planning tool, but it may also be used as an aid in monitoring and controlling projects. Again. it is important to remember 5.4