Page 295 - Mechanical Engineers' Handbook (Volume 2)

286 Analysis, Design, and Information Processing

system design engineering is to develop processes that are appropriate for a variety of process
users, some of whom may approach the design issue from a skill-based perspective, some
from a rule-based perspective, and some from a knowledge-based perspective.
A central purpose of systems engineering and management is to incorporate appropriate
methods and metrics into a methodology for problem solving, or a systems engineering
process or life cycle, such that, when it is associated with human judgment through systems
management, it results in a high-quality systems design procedure. By high-quality design,
we mean one that will, with high probability, produce a system that is effective and efficient
and trustworthy.
A systems design procedure must be specifically related to the operational environment
for which the final system is intended. Control group testing and evaluation may serve many
useful purposes with respect to determination of many aspects of algorithmic and behavioral
efficacy of a system. Ultimate effectiveness involves user acceptability of the resulting sys-
tem, and evaluation of this process effectiveness will often involve testing and evaluation in
the environment, or at least a closely simulated model of the environment, in which the
system would be potentially deployed.
The potential benefits of systems engineering approaches to design can be interpreted
as attributes or criteria for evaluation of the design approach itself. Achievement of many
of these attributes may often not be experimentally measured except by inference, anecdotal,
or testimonial and case study evidence taken in the operational environment for which the
system is designed. Explicit evaluation of attribute achievement is a very important part of
the overall systemic design process. This section describes the following:
1. A methodological framework for the design of systems, such as planning and deci-
sion support systems
2. An evaluation methodology that may be incorporated with or used independently of
the design framework
A number of characteristics of effective systems efforts can be identified. These form the
basis for determining the attributes of systems and systemic design procedures. Some of
these attributes will be more important for a given environment than others. Effective design
must typically include an operational evaluation component that will consider the strong
interaction between the system and the situational issues that led to the systems design
requirement. This operational evaluation is needed in order to determine whether a product
system or a service consisting of humans and machines:

1. Is logically sound
2. Is matched to the operational and organizational situation and environment extant
3. Supports a variety of cognitive skills, styles, and knowledge of the humans who must
use the system
4. Assists users of the system to develop and use their own cognitive skills, styles, and
knowledge
5. Is sufficiently flexible to allow use and adaptation by users with differing cognitive
skills, styles, and knowledge
6. Encourages more effective solution of unstructured and unfamiliar issues, allowing
the application of job-specific experiences in a way compatible with various accept-
ability constraints
7. Promotes effective long-term management