Enter the Tetrad Trade-off
Earlier we identified scope, quality, time and cost as the four
core target functions of project management (as viewed by a project
sponsor) or constraints (as viewed by the project manager). In practice,
however, project circumstances often prevail wherein these objectives
or constraints may not all be feasible or mutually compatible. This
is especially true when considerations of risk and uncertainty come
into play.
Moreover, the nature of some projects may be driven more by one
constraint than another. For example, a software product must work
well for a customer base to be retained. Therefore scope functionality
and quality will be paramount over time and perhaps cost. Conversely,
an exhibition will have a fixed opening day so that the scope of
the exhibition may have to be sacrificed to this deadline. Consequently,
in the course of managing the project process, the project manager
and his or her team must choose options and make decisions according
to the appropriate priorities. The relationship of these four parameters
can be viewed graphically as a Tetrad Trade-off as
shown in the Figure 5.
Figure 5
Consider four types of projects each one biased towards a different
quadrant of the tetrad. The first project, in the scope quadrant,
has defining the project scope as its priority (rather than developing
a defined scope). Good examples include research and development
(R & D) and defense projects. Such projects consequently tend
to be very uncertain in terms of quality, time and cost.
In many cases the scope is reasonably well defined, but the emphasis
must be on public safety so that quality is paramount. Examples
include infrastructure projects, passenger vehicles of all kinds
and high-end market products. As we have already suggested, any
project with an opening day deadline has time as its fixed constraint.
The opening day deadline of a national exposition, or the opening
night of a theater production are good examples. Or the emphasis
may be on a fixed budget such as appears to be the case in many
government-run projects — only to discover too late that in fact
scope and safety are paramount!
However, the inexperienced project manager should be cautioned
that the priority emphasis for a project may well shift during its
life cycle. For example: a project which is scope and quality oriented
at the outset may well shift towards cost and schedule towards the
end of its life cycle. An illustration of this might be a project
which, having experienced cost overruns, is running out of financing.
Conversely, a cost and schedule oriented project may well shift
towards scope and quality. An illustration of this might be a product
launch which needs to be moved "up-market" as a result
of new market competition. Typically, this latter shift is difficult
to accomplish in retrospect, which emphasizes the importance of
sound early project planning and vigilance during definition and
implementation.
Managing the Tetrad Trade-off with skill and understanding is a
very important part of managing a project. Rarely does a project
manager have the luxury of a project which has equally balanced
constraints, such that the achievement of all four is entirely feasible!
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Interesting
Variables
