) Briefly explain the following classifications of systems.
• Closed and open systems
• Deterministic and probabilistic systems
ii) State the features of systems theory
i) Classification of systems
i. Closed and open systems
Systems may be classified as open, relatively closed or closed. A closed system doesn‘t exchange resources with its environment. This implies that the system has no
input and no output relating it to the environment. E.g. A battery run and time control system of light signals placed temporarily on the road during repairs.
Open systems exchange resources with their environment via input and output, some of which are ill-defined or even unknown. An organisation is an open system. By injecting negative entropy into its operations (i.e. maintaining its order) an open system is able to adapt continually to its environment.
Between the two-extremes of closed and open systems is relatively closed system. These system exchange resources with their environment only through well defined input and output. Their input and output are defined when the system is designed, and the input are controlled to conform to these predefined form.
ii. Deterministic and probabilistic systems
The operation of a deterministic system is completely predictable e.g a computer program. The present state and the inputs of such a system fully determine its operations and its next state e.g. a microprocessor chip or a correct software package.
The outputs of probabilistic (or stochastic) systems can be predicted only in terms of the probability distribution of these values or of some aggregate measure such as the value. There is always uncertainty as to their actual value at any given time. Both organisations and ISs are probabilistic.
ii) Systems Theory
The systems approach or systems theory is an approach (abstract system of ideas) to problem solving – the problem being how to structure an organisation or analyse an IS – in which the entity being studied (an organisation or IS) is considered a system.
Features of the Systems Theory
The fundamental consideration affecting the design of information systems stem from Systems Approach. The approach has many facets but the following are the most salient:
1. All systems are composed of inter-related parts or sub-systems and the system can only be explained as a whole. This is known as holism or synergy. The systems view is that the whole is more than just some of the parts and those vital interrelationships will be ignored and misunderstood if the separate parts are studied in isolation.
2. Systems are hierarchical, that is, the parts and sub-systems are made up of other smaller parts. For example, a payroll system is a subsystem of the Accounting System, which is a sub of the whole organisation. One system is a sub of another…
3. The parts of a system constitute an indissoluble whole so that no part can be altered without affecting other parts. Many organisational problems arise once this principle is flouted or ignored. Changes to one department could create untold adverse effects on others – ripple effects: e.g. changing a procedure in one department could affect others e.g. changing a procedure in admissions department of a college will affect the academic departments- type of data captured, process
4. The sub-systems should work towards the goals of their higher systems and should not pursue their own objectives independently. When subsystems pursue their own objectives, a condition of sub-optimality arises, and with this the falling of the organisation is close at hand! Information systems designers should seek to avoid the sub-optimality problem!