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of those familiar with quantitative methods.
For each measure, it is important to address the
question of how that quantitative measure will be computed—that is, which measurement method is to be
used. One reason for doing this is that this step then
explicitly identifies those variables that are important in
meeting the system's goals and objectives.
Evaluating the likely outcomes of various
alternatives in terms of system effectiveness, the
underlying performance or technical attributes, and cost
before actual fabrication and/or programming usually
requires the use of a mathematical model or series of
models of the system. So a second reason for
specifying the measurement methods is that the
necessary models can be identified.
Sometimes these models are already available
from previous projects of a similar nature; other times, they need to be developed. In the latter case, defining
the measurement methods should trigger the necessary
system modeling activities. Since the development of
new models can take a considerable amount of time and
effort, early identification is needed to ensure they will
be ready for formal use in trade studies.
Defining the selection rule is the step of explicitly
determining how the outcome variables will be used to
make a (tentative) selection of the preferred alternative.
As an example, a selection rule may be to choose the
alternative with the highest estimated system
Functional Analysis Techniques
Functional analysis is the process of identifying, describing, and relating the functions a system must perform in order to fulfill its goals and objectives. Functional analysis is logically structured as a top-down
hierarchical decomposition of those functions, and
serves several important roles in the systems
• To draw out all the requirements the system
To help identify measures for system
effectiveness and its underlying performance
or technical attributes at all levels
To weed out from f...
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