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A mathematical approach to the modelling of systems, using techniques developed in control engineering to investigate systems behaviour in response to external stimuli. In their simplest forms, such models include an input (Xt), an output at a later time (Yt+n), and a transfer function S which links the two such that
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There is an important distinction between models that refer to continuous time and those in which the inputs and outputs occur (or are observed to occur) at discrete time scales: the latter are most common in geography, as in studies using lead-lag models.
Such models can be used to examine the likely behaviour of systems, and their impacts on their environments, even where the transfer function S is derived inductively without any knowledge of the causal mechanisms involved (as in work on limits to growth; cf. global futures and work on urban dynamics: Forrester, 1969).
A particular application of systems thinking which attracted some geographers in the 1960s and 1970s was general systems theory, an attempt pioneered by von Bertalanffy (1968) to develop general statements about the common properties of superficially different systems (the search for isomorphisms): such searches were exemplified by Woldenberg and Berry (1967), but dismissed as \'an irrelevant distraction\' by Chisholm (1967). (AMH)
References Chisholm, M. 1967: General systems theory and geography. Transactions, Institute of British Geographers 42: 45-52. Forrester, J.W. 1969: Urban dynamics. Cambridge, MA: MIT Press. von Bertalanffy, L. 1968: General systems theory: foundation, development, applications. New York: G. Brazillier; London: Allen Lane. Woldenberg, M.J. and Berry, B.J.L. 1967: Rivers and central places: analogous systems? Journal of Regional Science 7: 129-40.
Suggested Reading Bennett, R.J. and Chorley, R.J. 1978: Environmental systems: philosophy, analysis and control. London: Methuen. Wilson, A.G. 1981: Geography and the environment: systems analytical methods. Chichester and New York: John Wiley. |
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