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.

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

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

Types of model Descriptive models Predictive models Normative or optimising models Descriptive models

The systems approach Main 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.

Types of activities and information MANAGEMENT ACTIVITIES FUNCTIONAL ACTIVITIES

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

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

FUNCTIONAL SYSTEM CONTROL SYSTEM Design

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

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

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

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

Applying the systems approach OMNIS model an Overview Model of aN Information System in its organisational context Functional system Static component Dynamic Input/output Object Property Rule Behaviour Event Process

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

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 Process Input system Output system Rule Object Property Data capture Transact. input Query Report Event

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

The systems approach Advantages and disadvantages 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