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The systems approach

The systems approach. Churchman, C.W. (1968) The Systems Approach , Dell Publishing Co., New York. Ackoff, R.L. (1971) Towards a system of system concepts. Management Science , Vol. 17, No. 11, P. 661-671.

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The systems approach

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  1. The systems approach • Churchman, C.W. (1968) The Systems Approach, Dell Publishing Co., New York. • Ackoff, R.L. (1971) Towards a system of system concepts. Management Science, Vol. 17, No. 11, P. 661-671. • Von Bertalanffy L. (1968) General Systems Theory: Foundations, Development, Applications, Penguin, London.

  2. Definition of the system • A system is an assembly of parts or components existing together in an organised way • The assembly is of particular human interest • Parts are affected by being in the system - they change if they leave • The assembly does something - it has an aim Open University definition

  3. Types of systems (Checkland, 1981) • Natural systems • Designed physical systems • Designed abstract systems • Human activity systems INFORMATION SYSTEMS

  4. Types of model • Predictive models • Normative or optimising models • Descriptive models

  5. The systems approachMain concepts and assumptions • basic concepts • described in terms of input, output, process, boundary, environment • input and output - static objects transformed by dynamic processes • control system is essential for unpredictable systems • The state space approach - views processes (update processes) as transformations between one state to another. A state at a given instant consists of the objects in the system at that instant.

  6. Types of activities and information MANAGEMENT ACTIVITIES FUNCTIONAL ACTIVITIES

  7. Types of activities and information(EXAMPLES) • functional activities • processing a shipment order • paying employee wages • processing sales • ... • management activities • scheduling jobs • hiring and firing staff • managing departmental budgets • checking organisational performance against objectives • deciding on new markets or strategies • ...

  8. FUNCTIONAL SYSTEM Process E E Input Output Standard Sensor Activating unit Control device CONTROL SYSTEM

  9. CONTROL SYSTEM FUNCTIONAL SYSTEM Design

  10. FUNCTIONAL SYSTEM Information Information system Changes Information Management system CONTROL SYSTEM Applying the systems approach

  11. FUNCTIONAL SYSTEM Event Information Input system HCS Information base Simulation system Message system Changes Information system Output system Information Management system CONTROL SYSTEM

  12. Interaction of functional and control systems 1. The event occurs in the functional system 2. The human computer system (input system) records details concerned with the functional system event 3. The input system initiates appropriate simulation system process 4. The simulation system process updates the information base 5. The user initiates the human computer system (output system) process to start the appropriate message system process to obtain information from information base 6. The user performs the management system activity using the information obtained 7. Possible changes are made to the functional system

  13. Management system components Information system Internal users External users Informational Decision making Interpersonal Management system

  14. Functional system Static component Dynamic component Input/output Rule Behaviour Object Property Event Process Applying the systems approachOMNIS modelan Overview Model of aN Information System in its organisational context

  15. OMNIS model Control system Information system Management system Simulation system Message system Human computer system Input system Output system Rule base Information base Process Data capture Transact. input Query Report Rule Object Property Event

  16. OMNIS model ORGANISATION Functional system Control system Static component Dynamic component Information system Management system Input/output Rule Behaviour Simulation system Message system Human computer system Object Property Event Process Rule base Information base Input system Output system Process Data capture Transact. input Query Report Rule Object Property Event

  17. OMNIS Principles • Non-redundancy - model fact only once • Completeness - model all the relevant facts • Accuracy - do not invent facts (model only what is in the description) • Clarity • model fact as an object rather than a property • only model important properties

  18. The systems approach Advantages and disadvantages • Advantages • description of system using intuitively familiar notions (input, output, process) • decomposition • notion of control system • description suitable for communication • Disadvantages • possibility of non-unique descriptions • there is no guidance concerning level of detail (possibility of incompleteness of description) • no method is suggested to apply approach

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