USE OF THE WBS TO DEVELOP ACTIVITIES
An important role of the WBS is to facilitate the identification and development of project activities. The specific mechanism to be used to develop activities is described in this section, as is a set of criteria for defining activities.
After ensuring that the entire scope of the project is addressed, the primary function of the WBS is to facilitate the identification and definition of the activities that need to be performed in the project. The WBS was described previously as noun-based down through the work packages. Activities are verb-based because that is where the action is. This was also shown in Figure 2-13. The WBS provides the outline structure for Gantt charts and network planning. The WBS outlines what work will be performed, and the activities describe the actions necessary to perform that work. This is shown in Figure 2-14 for a hypothetical Hacker Analysis System Project.
In the figure, the WBS elements are in bold and are in adjective/noun form. The activities are in italics in verb/adjective/noun form at the level below the WBS.
This example shows the relationship of the WBS to the activities in the schedule and used in network planning. The individual activities are linked in the project management software into a precedence network and displayed in Gantt format on the screen and when printed out on hard copy.
The manner in which the WBS is arrayed can make schedules easier to read and to use. Put the Project Management element at the top of the WBS and numbered 1.0 as shown in the figure. And if there is any natural process flow at Level 2 of the WBS, have it go from left to right in the graphic version of the WBS or top to bottom in the outline version; then the schedules will be displayed more naturally.
Although the WBS is not a scheduling tool, it would be putting one’s head in the sand to not recognize that some phasing exists in most projects, no matter how simple the project. This is especially the case in “results” projects where standard steps or stages are followed.
A useful device to assist in scheduling is to establish a special work package under “Project Management” for the start and completion events of the project. Included in the work package are the two zero-duration activities that identify the start and completion. These activities have two advantages: one is that you have an anchor from which to link all successor activities in the planning network; the second is that by linking them to one start point, if there is a delay in the start of the project, it can be easily accommodated by changing only the start date of one event.
In Figure 2-15, the data of Figure 2-14 have been entered into Microsoft Project application software to illustrate the use of the WBS as an outline for structuring the schedule.
It should be clear that if we follow the 100 percent rule and input the WBS into the project management software, it is an easy and swift task to identify all the activities in the project and to array them in a logical schedule format. The activities are the basic building blocks of the project, and as has been repeated several time, the goal of the WBS is to make sure all these building blocks are identified.
FIGURE 2-15 Hacker Analysis System (HAS) Project
Experience has shown that defining activities or tasks is not as easy as it looks. Too many times they are inadequately described, and poor schedules and communication problems result. Activity definition is extremely important because activities are the building blocks for planning and controlling the project.
An activity normally has an expected duration, an expected cost, and expected resource requirements. Also, a single person or organization responsible and accountable for the work performed characterizes an activity.
Although infrequently specified explicitly at the detail level in project planning, activities have performance requirements as well, and most activities also have specified outputs or results. If the activity is vague, it needs to be redefined.
LIST OF CHARACTERISTICS OF ACTIVITIES
Work is performed and described in terms of a verb, adjective, and noun—there is action performed.
A single person or organization is responsible for the work—more than one resource may be assigned to an activity, but one person is in charge of delivering the output. If this is not the case, the item needs further decomposition or joint responsibilities need to be clarified.
It has defined start and finish points—there is either a specific predecessor activity or event that must be completed first or a specific date on which the activity is scheduled to start; the scheduled end date is based on the estimated duration, baseline duration, or scheduled duration of the activity.
There is a tangible output or product at completion (usually)—projects occasionally have level-of-effort activities or support activities without clearly defined outputs; however, the primary activities have defined and measurable outputs. The point at which an activity is completed is determined by the availability of an output product that is used as input by a successor activity.
It fits logically under an existing WBS element—if it does not, then the activity is not part of the project, the WBS needs modification, or the activity is ambiguous and needs redefinition.
It is of a size and duration that is sufficient for control—activities that are too long do not provide sufficient time for corrective action if problems arise, and activities that are too short can make the cost of the control more expensive than a problem that may arise. Kerzner suggests that activities ideally be 80 hours and less than 2–4 weeks but that this may not be possible on very large projects.
Actual schedule status data can be collected for the activity—for schedule control, the start and end points must be sufficiently defined that the start and finish of the activity can be reported.
Actual cost (person-hour) data can be collected for the activity or work package that contains the activity—for cost or resource control, actual cost data or the actual expenditure of resources can be collected; obviously, if tracking of actual expenditures is not required, this principle can be ignored.
The labor and costs necessary to perform the activity can be estimated—the resource requirements must be able to be determined in the planning phase.
The output of the activity is known or can be identified—outputs are frequently pieces of paper or other tangible proof of the activity’s being completed.
The activity represents a significant effort in support of project objectives—trivial or incidental activities need not be included.
Zero-duration activities are milestones or events that represent the start or completion of another activity or set of activities. They should be included at the start and finish of the project and included to identify completion of key activities or groups of activities.
A most important consideration is this: The activity may not be performed if it is not in the plan. In fact, the reason to have a written plan is to make sure the need for the activity is communicated to the appropriate stakeholders, including those people who are responsible for predecessor and successor activities and the person responsible for performing the activity.
Scrutinizing the activities identified in the Hacker Analysis System (HAS) project in Figures 2-14 and 2-15 reveals how the preceding characteristics are present in the WBS.
The HAS requirements specification and the HAS design specification are well-defined documents, and the activities involved are all clear. The outputs are tangible—something is done to the document.
The activities of coding the software are similarly clearly defined. The output would be completed software code, probably in hard copy as well as digital form, depending on the normal practices of the organization. Unit test is usually defined by the completion of a document provided by the quality control organization or someone providing a similar independent verification function that certifies that the test was performed and completed as specified.