Project Management Simply Explained - A Logical Framework to Help Your Understanding


Introduction | PMBoK | Sequence | LifeCycle | Hierarchy
 | Tetrad Trade-off | Success

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!

Interesting Variables  Interesting Variables

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