2 Contemplative Questions What is systems thinking?Why do ‘systems thinkers’ get promoted?How does the field of information systems benefit from concepts of systems theory?How can we use these concepts in the real world?
3 Systems Thinking System A system is an interrelated set of business procedures used within one business unit working together for a purposeA system has nine characteristicsA system exists within an environmentA boundary separates a system from its environment2.3
4 Characteristics of a System ComponentsInterrelated ComponentsBoundaryPurposeEnvironmentInterfacesInputOutputConstraintsOn a sheet of paper, define each of these terms in your own words.
6 Systems Thinking Important System Concepts DecompositionThe process of breaking down a system into smaller componentsAllows the systems analyst to:Break a system into small, manageable subsystemsFocus on one area at a timeConcentrate on component pertinent to one group of usersBuild different components at independent times
7 Systems Thinking Important System Concepts ModularityProcess of dividing a system into modules of a relatively uniform sizeModules simplify system designCouplingSubsystems that are dependent upon each other are coupledCohesionExtent to which a subsystem performs a single functionWhich is better:More or less modularity? High or low coupling? High or low cohesion?Suppose you work as a systems analyst in a large organization. Your boss comes into your office and gives you a project requiring changes to another department’s system. Would you rather the existing systems have high or low coupling? high or low cohesion? more or less modularity?
8 Systems Thinking Important System Concepts Logical vs. Physical ModelingLogical System DescriptionPortrays the purpose and function of the systemDoes not tie the description to a specific physical implementationPhysical System DescriptionFocuses on how the system will be materially constructed
9 Systems Thinking Benefits Identification of a system leads to abstractionFrom abstraction you can think about essential characteristics of specific systemAbstraction allows analyst to gain insights into specific system, to question assumptions, provide documentation and manipulate the system without disrupting the real situationExample. Identify a system used by the university. Use the characteristics of systems in general to describe your system. What insight can you gain from this exercise?
10 Systems Thinking Applying Systems Thinking to Information Systems Information systems are subsystems in larger organizational systemsData flow diagrams represent information systems as systemsInputsOutputsSystem boundariesEnvironmentSubsystemsInterrelationships2.10
11 Decomposition Example Figures 8-4 and 8-5.What system characteristics are demonstrated in these pictures?What do the diagrams tell you?Which diagram is more useful?Show decomposition of the system, balancing between diagrams, inputs, outputs, boundary, components, etc.Context diagram in top left shows the context of the system within its environment. It is purposely simple.Right hand side shows more detail of Food Ordering System.Each is useful in its own right. Context shows a quick summary. Level 0 on the right is more detailed. This is the beauty of decomposition—more information conveniently represented.