There are many possible answers. Project management is
needed in large construction jobs, in implementing new informa-
tion systems, in new product development/marketing, in creating a
new assembly line, and so on.
Project organizations make sure existing programs continue to
run smoothly while new projects are successfully completed.
The three phases involved in managing a large project are:
PERT and CPM help answer questions relating to which task
elements are on (or likely to be on) the critical path and to proba-
ble completion times for the overall project. Some specific ques-
When will the entire project be completed?
Which are the critical activities or tasks in the project; that
is, the activities that will delay the entire project if com-
pleted behind schedule?
Which are the noncritical activities; that is, those that can
run behind schedule without delaying the whole project?
How far behind schedule can these activities run without
disrupting the completion time?
What is the probability that the project will be completed
by a specific date?
At any particular date, is the project on schedule, behind
schedule, or ahead of schedule?
On any given date, is the money spent equal to, less than,
or greater than the budgeted amount?
Are there enough resources available to finish the project
If the project is required to be finished in a shorter amount
of time, what is the least-cost way to accomplish this?
WBS is a hierarchial subdivision of effort required to achieve
an objective. It defines a project by breaking it down into manage-
able parts and even finer subdivisions.
A Gantt chart is a visual device that shows the duration of
tasks in a project. It is a low cost means of ensuring that (1) all ac-
tivities are planned for, (2) their order of performance is planned
for, (3) the activity times are recorded, and (4) the overall project
time is developed.
The difference between
is that activities are
shown on arrows in the former and on the node in the latter. We
in this chapter.
Any late start or extension of an activity on the critical path
will delay the completion of the project.
To crash an activity, the project manager would pay money
to add resources (overtime, extra help).
Activity times used in PERT are assumed to be described by
a Beta probability distribution. Given optimistic (
), and most likely (
), completion times, average or expected
time is given by:
and the variance by:
Early start (ES) of an activity is the latest of the early finish
times of all its predecessors. Early finish (EF) is the early start of
an activity plus its duration. Late finish (LF) of an activity is the
earliest of the late start times of all successor activities. Late start
(LS) of an activity is its late finish less its duration.