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After the assumptions are discussed, the moderator leads a brainstorming session to gener-
ate the WBS. The team breaks the project down into between 10 and 20 tasks, represent-
ing all of the project activities that must be performed. Once the team is comfortable with
the WBS and the assumptions, it will feel much more knowledgeable about the context in
which it will be developing the software. This, in turn, will make everyone more comfort-
able with the team’s estimates.
Individual preparation
After the kickoff meeting, the moderator writes down all of the assumptions and tasks that
were generated by the team during the kickoff meeting and distributes them to the esti-
mation team. Each team member independently generates a set of preparation results, a
document which contains an estimate for each of the tasks, any assumptions that the team
member made in order to create the estimates, and any additional tasks that should be
included in the WBS but that the team missed during the kickoff meeting. (Figure 3-1
shows the format of the individual preparation results.) Each team member builds prepa-
ration results by first filling in the tasks, and then estimating the effort for each task. An
estimate for each task should be added to the “Tasks to achieve goal” section of the prepa-
ration results; the “Time” column should contain the estimate for each task.
Task list Assumptions
Tasks to achive goal Time 1.
2.
3.
4.
5.
6.
Calendar waiting time, delays 7.
8.
9.
10.
11.
12.
Project overhead tasks 13.
14.
15.
FIGURE 3-1. Individual preparation results
Each estimate should be made in terms of effort, not calendar time. This means that if the
unit of estimation is “days,” then the estimate should be for the total number of person-
days spent. For example, if a task will require one person to work for 10 days and a second
person to work for 6, the estimate should be 16 person-days (or 3.2 person-weeks, assum-
ing a 5-day week). If both people are working at the same time so that their effort overlaps
entirely, the calendar time required to do this task is 10 days.
Usually, effort does not overlap perfectly like this; this kind of parallel effort will be factored
in later, when the project schedule is created (see Chapter 4). However, one important
ESTIMATION 43