12
I.
Introduction
Finally, after having taken into account each of the five phases in as
much detail as required (but always being limited by the costs involved
and by lack of information), the analyst is prepared to use the model for
1. Economic experimentation. The system time scale can be compressed
by computer simulation so that existing and proposed operations can be
examined in relatively reasonable times.
2. Extrapolation. Extreme ranges of operating conditions can be examined without incurring damages that might arise in a real physical
system.
3. Study of commutability and evaluation of alternate policies. Elements of
the system can be rearranged, new factors introduced, and the design of
future systems evaluated.
4. Effect of stochastic variables. Random effects can be introduced with
known statistics for the random variables.
5. Sensitivity. The effect on the outputs of changes in individual and
joint variables and parameters can be examined.
All of the above uses of a model pertain to design and operation without
actually undertaking the physical construction of the system.
In his work the systems analyst is particularly concerned with answers
to the following questions:
1. For what organization or group of people is the system being
developed?
2. What are the goals and objectives of the users of the system and
other systems that interact with it?
3. What alternative systems should be considered?
4. What effects or consequences are imposed on the users by the various
prospective systems?
5. What are the criteria for comparing and ranking alternative systems
and for evaluating the consequences of building the system on objectives
external to the system under consideration?
6. How reliable are the estimates of system costs and revenues, and of
performance, and how does the level of reliability affect the choice of
alternatives? How were the data used in the analysis obtained, and how
reliable are they?
7. Are the consequences of the system alternatives measured, evaluated,
and presented to the decision makers and to the community in which they
function in a fashion that is understandable and usable?
The systems approach certainly opens the door for an expansion of analytical activity, and it involves a rather wide body of mathematical tools. It
I.
Introduction
Finally, after having taken into account each of the five phases in as
much detail as required (but always being limited by the costs involved
and by lack of information), the analyst is prepared to use the model for
1. Economic experimentation. The system time scale can be compressed
by computer simulation so that existing and proposed operations can be
examined in relatively reasonable times.
2. Extrapolation. Extreme ranges of operating conditions can be examined without incurring damages that might arise in a real physical
system.
3. Study of commutability and evaluation of alternate policies. Elements of
the system can be rearranged, new factors introduced, and the design of
future systems evaluated.
4. Effect of stochastic variables. Random effects can be introduced with
known statistics for the random variables.
5. Sensitivity. The effect on the outputs of changes in individual and
joint variables and parameters can be examined.
All of the above uses of a model pertain to design and operation without
actually undertaking the physical construction of the system.
In his work the systems analyst is particularly concerned with answers
to the following questions:
1. For what organization or group of people is the system being
developed?
2. What are the goals and objectives of the users of the system and
other systems that interact with it?
3. What alternative systems should be considered?
4. What effects or consequences are imposed on the users by the various
prospective systems?
5. What are the criteria for comparing and ranking alternative systems
and for evaluating the consequences of building the system on objectives
external to the system under consideration?
6. How reliable are the estimates of system costs and revenues, and of
performance, and how does the level of reliability affect the choice of
alternatives? How were the data used in the analysis obtained, and how
reliable are they?
7. Are the consequences of the system alternatives measured, evaluated,
and presented to the decision makers and to the community in which they
function in a fashion that is understandable and usable?
The systems approach certainly opens the door for an expansion of analytical activity, and it involves a rather wide body of mathematical tools. It