Page 276 - Mechanical Engineers' Handbook (Volume 2)

4 Systems Engineering Methodology and Methods 267

4. Identify decisions, events, and event outcomes and the relations among them such
that a structure of the possible paths among options, alternatives, or decisions and
the possible outcomes of these emerge (impact assessment).
5. Identify uncertainties and risks associated with the environmental influences affect-
ing alternative decision outcomes (probability identification).
6. Identify measures associated with the costs and benefits or attributes of the various
outcomes or impacts that result from judgment and choice (worth, value, or utility
measurement).
7. Search for and evaluate new information, and the cost-effectiveness of obtaining
this information, relevant to improved knowledge of the time-varying nature of event
outcomes that follow decisions or choice of alternatives (information acquisition
and evaluation).
8. Enable selection of a best course of action in accordance with a rational procedure
(decision assessment and choice making).
9. Reexamine the expected effectiveness of all feasible alternative courses of action,
including those initially regarded as unacceptable, prior to making a final alternative
selection (sensitivity analysis).
10. Make detailed and explicit provisions for implementation of the selected action
alternative, including contingency plans, as needed (planning for implementation of
action).

These objectives are, of course, very closely related to the aforementioned steps of the
framework for systems engineering. To accomplish them requires attention to and knowledge
of the methods of systems engineering such that we are able to design product systems and
service systems and also enabling systems to support products and services. We also need
to select an appropriate process, or product line, to use for management of the many activities
associated with fielding a system. Also required is much effort at the level of systems man-
agement so that the resulting process is efficient, effective, equitable, and explicable. Thus,
it is necessary to ensure that those involved in systems engineering efforts be concerned with
technical knowledge of the issue under consideration, able to cope effectively with admin-
istrative concerns relative to the human elements of the issue, interested in and able to
communicate across those actors involved in the issue, and capable of innovation and out-
scoping of relevant elements of the issue under consideration. These attributes (technical
knowledge, human understanding and administrative ability, communicability, and innova-
tiveness) are, of course, primary attributes of effective management.

4 SYSTEMS ENGINEERING METHODOLOGY AND METHODS

A variety of methods are suitable to accomplish the various steps of systems engineering.
We shall briefly describe some of them here.

4.1 Issue Formulation
As indicated above, issue formulation is the step in the systems engineering effort in which
the problem or issue is defined (problem definition) in terms of the objectives of a client
group (value system design) and where potential alternatives that might resolve needs are
identified (system synthesis). Many studies have shown that the way in which an issue is
resolved is critically dependent on the way in which the issue is formulated or framed. The