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SYSTEMS

A system is a collection of elements such as people, = resources,=20 concepts, and procedures intended to perform an identifiable function or = serve a=20 goal. A clear definition of that function is important to the design of = an=20 information system. For instance, the purpose of an air defense system = is to=20 protect ground targets, not just to destroy attacking aircraft or = missiles.

Levels and Structures of Systems=20

The notion of levels (or a hierarchy) of systems reflects that all = systems=20 are actually subsystems, since all are contained within some = larger=20 system. For example, a bank system includes such subsystems as the = commercial=20 loan system, the consumer loan system, the savings system, and so = on.

Systems are divided into three distinct parts: inputs, processes, = and=20 outputs. They are surrounded by an environment and frequently include a = feedback=20 mechanism that controls some aspect of the operation. In addition, a = human, the=20 decision maker, is considered a part of the system.

Inputs include those elements that enter the system. = Examples of=20 inputs are raw materials entering a chemical plant, patients admitted = to a=20 hospital, or data inputted into a computer.=20

All the elements necessary to convert or transform the inputs into = outputs=20 are included in the system=92s processes. For example, in a chemical = plant a=20 process may include heating the materials, following operating = procedures,=20 operating the materials-handling subsystem, and utilizing employees = and=20 machines. In a computer, a process may include activating commands, = executing=20 computations, and storing information.=20

Outputs describe the finished products or the consequences = of being=20 in the system. For example, fertilizers are one output of a chemical = plant,=20 cured people are the output of a hospital, and reports may be the = output of a=20 computerized system.=20

The connections among subsystems are the flow of information and = materials=20 among the subsystems. Of special interest is the flow of information = from the=20 output component to a control unit (or a decision maker) concerning = the=20 system=92s performance. Based on this information, which is called=20 feedback, the inputs or the processes may be modified.=20

The environment of the system is composed of several = elements that=20 lie outside it, in the sense that they are not inputs, outputs, or = processes.=20 However, they have a significant impact on the system=92s performance = and=20 consequently on the attainment of its goals. One way to identify the = elements=20 of the environment is by answering two questions:=20

Is the element significant to the system=92s goals?=20
Is it possible for the decision maker to manipulate this=20 element?

If, and only if, the answer to the first question is yes, and the = answer=20 to the second is no, should the element be considered part of the=20 environment.

A system is separated from its environment by a boundary. The = system is=20 inside the boundary, whereas the environment lies outside. Boundaries = may be=20 physical or nonphysical. For example, a system can be bounded by = time.

Because every system can be considered a subsystem of another, the=20 application of system analysis may never end. Therefore it is necessary, = as a=20 matter of practicality, to confine the system analysis to defined = manageable=20 boundaries. Such confinement is termed closing the system. A = closed=20 system represents one extreme along a continuum of independence. = (The=20 open system* is at the other extreme.) A closed system is totally = independent, whereas an open system is very dependent on its environment = (and/or=20 other systems). The open system accepts inputs (information, energy, and = materials) from the environment and may deliver outputs into the=20 environment.

When determining the impact of changes on an open system, it is = important to=20 check the environment, the related systems, and so on. In a closed = system,=20 however, it is not necessary to conduct such checks because it is = assumed that=20 the system is isolated. Traditional computer systems like transaction = processing=20 systems (TPSs) are considered to be closed systems. The newer decision = support=20 systems (DSSs) are open.

System Effectiveness and Efficiency=20

Systems are evaluated and analyzed along two major dimensions: = effectiveness=20 and efficiency. Effectiveness is the degree to which the right = goals are=20 achieved. It is concerned with the results or the outputs of a system. = The=20 outputs may be the total sales of a company or of a salesperson, for = example.=20 Efficiency is a measure of the use of inputs (or resources) to = achieve=20 results. An example of efficiency might be how much money is used to = generate a=20 certain level of sales. An interesting way to distinguish between the = two terms=20 is as follows:=20

Effectiveness =3D Doing the =93right=94 thing
Efficiency =3D = Doing the =93thing=94=20 right

General Systems Theory=20

The term general systems theory refers to the discipline that = deals=20 with the field of systems and their analysis, design, and improvement. = It=20 includes the concepts, methods, and knowledge pertaining to the field of = systems=20 and systems thinking. It is an interdisciplinary, holistic approach to = the study=20 of systems. (For details, see J. P. Van Gigch, Applied General = Systems=20 Theory, 2nd ed., New York: Harper and Row, 1978.)=20

The term open system* in IT has a different meaning. It = refers to the=20 ability of software to run on any hardware.=20

SYSTEMS

Systems are divided into three distinct parts: inputs, processes, = and=20 outputs. They are surrounded by an environment and frequently include a = feedback=20 mechanism that controls some aspect of the operation. In addition, a = human, the=20 decision maker, is considered a part of the system.

Inputs include those elements that enter the system. = Examples of=20 inputs are raw materials entering a chemical plant, patients admitted = to a=20 hospital, or data inputted into a computer.=20

Outputs describe the finished products or the consequences = of being=20 in the system. For example, fertilizers are one output of a chemical = plant,=20 cured people are the output of a hospital, and reports may be the = output of a=20 computerized system.=20

Is the element significant to the system=92s goals?=20 Is it possible for the decision maker to manipulate this=20 element?

If, and only if, the answer to the first question is yes, and the = answer=20 to the second is no, should the element be considered part of the=20 environment.

A system is separated from its environment by a boundary. The = system is=20 inside the boundary, whereas the environment lies outside. Boundaries = may be=20 physical or nonphysical. For example, a system can be bounded by = time.

A system is separated from its environment by a boundary. The = system is=20 inside the boundary, whereas the environment lies outside. Boundaries = may be=20 physical or nonphysical. For example, a system can be bounded by = time.

Effectiveness =3D Doing the =93right=94 thingEfficiency =3D = Doing the =93thing=94=20 right

*The term open system in IT has a different meaning. It = refers to the=20 ability of software to run on any hardware.=20

Is the element significant to the system=92s goals?=20
Is it possible for the decision maker to manipulate this=20 element?

Effectiveness =3D Doing the =93right=94 thing
Efficiency =3D = Doing the =93thing=94=20 right

The term open system* in IT has a different meaning. It = refers to the=20 ability of software to run on any hardware.=20