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Unformatted text preview: ity in ease of use between them. They are all difficult to use, and the training materials (tutorials and
manuals) that come with the software are often not very good. In addition, it is hard to find time to work
through a tutorial without being interrupted repeatedly, which means that self-learning is difficult. The most
efficient way to learn is to take a class.
Before signing up for a class, check out the instructor’s knowledge of project management. There are people
teaching the software who know very little about project management itself; when you have questions, they
won’t be able to answer them. You should expect to spend from two to three days of classroom time becoming really proficient with the software—a good investment, considering the time the software can save
you in the long run. A BRIEF HISTORY OF SCHEDULING
Until around 1958, the only tool for scheduling projects was the bar chart (see Figure 5-1). Because Henry
Gantt developed a complete notational system for showing progress with bar charts, they are often called
Gantt charts. They are simple to construct and to read, and they remain the best tool for communicating to
team members what they need to do in given time frames. Although arrow diagrams tend to be too
complicated for some teams, it is often helpful to show such a diagram to the people doing the work so that
they understand interdependencies among tasks and why it is important that they complete certain tasks on
time. Figure 5-1 A sample bar chart.
CPM: Critical Path Method PERT: Performance Evaluation & Review Technique
Gantt charts have one serious drawback—determining the impact of a slip of one task on the rest of the
project is very difficult. That is, if Collect Data in Figure 5-1 gets behind, it is hard to tell how it will affect
the rest of the work, because the bar chart does not show the interdependencies of the work.
To overcome this problem, two methods of scheduling were developed in the late 1950s and early 1960s that
used arrow diagrams to capture the sequential and parallel relationships among project activities. One method
was called Critical Path Method (CPM), developed by du Pont; the other, Performance Evaluation and
Review Technique (PERT), was developed by the Navy and the Booze, Allen and Hamilton consulting group.
Although it has become customary to call all arrow diagrams PERT networks, strictly speaking, the PERT
method makes use of probability techniques, whereas CPM does not. In other words, using PERT allows you
to calculate the probability that an activity will be completed by a certain time, whereas CPM does not. NETWORK DIAGRAMS
Arrow diagrams like those in Figure 5-2 are used to show the sequence in which work is performed. In these
diagrams Task A is done before B, while Task C is done in parallel with them.
The network in the bottom half of Figure 5-2 uses activity-on-arrow notation, in which the arrow represents
the work being done and the circle represents a...
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This document was uploaded on 09/27/2013.
- Fall '13