Page 282 - Mechanical Engineers' Handbook (Volume 2)

4 Systems Engineering Methodology and Methods 273

must be made among allocation of resources for formulation, analysis, and interpretation of
ideas in the issue formulation step itself. If there is an emphasis on idea formulation, we
shall likely generate too many ideas to cope with easily. This will lead to a lack of attention
to detail. On the other hand, if idea formulation is deemphasized, we shall typically en-
courage defensive avoidance through undue efforts to support the present situation or a rapid
unconflicted change to a new situation. An overemphasis on analysis of ideas is usually time
consuming and results in a meeting that seems to drown in details. There is inherent merit
in encouraging a group to reach consensus, but the effort may also be inappropriate, since
it may encourage arguments over concerns that are ineffective in influencing judgments.
Deemphasizing the analysis of identified ideas will usually result in disorganized meet-
ings in which hasty, poorly thought-out ideas are accepted. Postmeeting disagreements con-
cerning the results of the meeting are another common disadvantage. An emphasis on
interpretation of ideas will produce a meeting that is emotional and people centered. Mis-
understandings will be frequent as issues become entrenched in an adversarial, personality-
centered process. On the other hand, deemphasizing the interpretation of ideas results in
meetings in which important information is not elicited. Consequently, the meeting is awk-
ward and empty, and routine acceptance of ideas is a likely outcome.

4.2 Issue Analysis
In systems engineering, issue analysis involves forecasting and assessing of the impacts of
proposed alternative courses of action. In turn, this suggests construction, testing, and vali-
dation of models. Impact assessment in systems engineering includes system analysis and
modeling and optimization and ranking or refinement of alternatives. First, the options or
alternatives defined in issue formulation are structured, often as part of the issue formulation
effort, and then analyzed in order to assess the anticipated impacts that may result from their
implementation. Second, a refinement or optimization effort is often desirable. This is di-
rected toward refinement or fine-tuning a viable alternative and parameters within an alter-
native, so as to obtain maximum needs satisfaction, within given constraints, from a proposed
policy.
To determine the structure of systems in the most effective manner requires the use of
quantitative analysis to direct the structuring effort along the most important and productive
paths. This is especially needed when time available to construct structural models is limited.
Formally, there are at least four types of self-interaction matrices: nondirected graphs, di-
rected graphs (or digraphs), signed digraphs, and weighted digraphs. The theory of digraphs
and structural modeling is authoritatively presented in Ref. 12 and a number of applications
to what is called interpretative structural modeling are described in Refs. 3, 13, 14, and
15. Cognitive map structural models are considered in Ref. 16. A development of struc-
tural modeling concepts based on signed digraphs is discussed in Ref. 17. Geoffrion
has been especially concerned with the development of a structured modeling methodol-
ogy 18,19 and environment. He has noted 20 that a modeling environment needs five quality-
and productivity-related properties. A modeling environment should:
1. Nurture the entire modeling life cycle, not just a part of it
2. Be hospitable to decision- and policy-makers as well as to modeling professionals
3. Facilitate the maintenance and ongoing evolution of those models and systems that
are contained therein
4. Encourage and support those who use it to speak the same paradigm-neutral language
in order to best support the development of modeling applications
5. Facilitate management of all the resources contained therein