The Dictionary of Human Geography (192 page)

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Authors: Michael Watts

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space syntax
An approach to studying the spatial structure of cities using mathematical tools to describe their complexity. For example, the street system may be analysed topologically by calculating the complexity distance for each street that is, the minimum number of links needed (i.e. streets traversed) to reach all other streets in the city (see top ology). The measures extend beyond three dimensional descriptions of the elements of the built environment themselves to assess ments of how they are integrated as in the use of isovists to identify the area visible from any point, either at street level or, say, from a window on a building's fourth floor. (In geographic information systems these are termed viewsheds.) Such representations, using maps and graphs as well as numerical indices, allow the city's ?navigability' to be assessed how easy is it to move about and to get from one point to another? with tech niques that can be applied at any scale (how easy is it to get around an airport terminal, for example?). (NEW PARAGRAPH) Using their syntactical representations of the urban built environment, workers at the Space Syntax Laboratory at the Bartlett School of Architecture, University College London have studied commuting and other movements, linking flows to the urban struc ture and thereby providing means for predict ing future traffic patterns and transport system demands. rj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Hiller (1996); Hiller and Hanson (1984). See also http://www.spacesyntax.org/ (NEW PARAGRAPH)
space-economy
The idea that economic processes extend across geographical space, thereby influencing their operation and out come. Walter Isard (1956) coined the term, using it as the basis for his new discipline of regional science. In his (much earlier) devel opment of location theory, August Losch (1954 [1940]) had already shown that eco nomic competition in space does not have the same beneficial outcomes claimed in standard economic theory, because competi tion is monopolistic in spatially extensive markets (see neo classical economics). Location theory and regional science devel oped a series of related claims showing how space makes a difference to economic theory, making the term popular in the 1950s and 1960s. Within this tradition, spatial struc tures, a consequence of rational economic decision making, drive equilibrium outcomes and social welfare implications that differ from those of mainstream, a spatial economic the ory. Since 1990, with a revival of this tradition of work in geographical economics, the term has regained its popularity (Fujita, Krugman and Venables, 1999; see also new economic geography). (NEW PARAGRAPH) A parallel usage can be found within geo graphical interventions in marxism and polit ical economy, particularly among theorists whose intellectual socialization was influenced by spatial science and location theory, and who subsequently became highly critical of these formulations. Thus Harvey (1999 (NEW PARAGRAPH) ) used the term to describe how the geographical organization of capitalism shapes its dynamics and evolution, calling into question some core beliefs of the conventional a spatial Marxist critique of capitalism, and Sheppard and Barnes (1990) took these arguments still further in their analysis of the capitalist space economy. In this view, space qualitatively complicates the contradictions, crises and cLass struggles that are character istic of capitalism. The spaces and places produced through accumuLation and compe tition dynamics become barriers for future accumulation; conflict between places can cut across and undermine class struggle; and individual agents find it all but impossible to undertake actions that are in their long term as well as their immediate interests. Again, taking account of the spatial extension of economic processes requires adjustments to conventional, a spatial political economy. In this case, however, in contradistinction to regional science and location theory, analysis focuses on the dynamical dialectical relation between economic processes and the spatiaL ity they shape and are in turn shaped by (see diaLectic), rather than on assumed spatial structures and their impact on spatial eco nomic equilibria. (NEW PARAGRAPH) As economic geography has subsequently moved to a conception of economy that emphasizes the inseparability of the economic from other societal and biophysical processes, thereby calling into question any theory that seeks to separate or prioritize economic rela tive to these other processes, so once again the term ?space economy? has fallen out of favour (see also cuLturaL turn; institu tionaL economics). es (NEW PARAGRAPH)
space-time forecasting models
Statistical models that attempt to forecast the evolution of variables over both time and space (e.g. sets of regions). These models are usually of the general regression form and forecast the future value of a variable and an observation unit in terms of (a) lagged exogenous or explanatory variables, (b) its own past values and (c) the lagged values for neighbouring or influencing spatial observation units, thus capturing the impacts of spatial diffusion. These models have been used to forecast both economic and demographic changes, and in studies of epidemics and the modelling of disease. Lwh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Bennett (1979). (NEW PARAGRAPH)
spatial analysis
The application of quanti tative methods in LocationaL anaLysis within human geography and sometimes used as a synonym for that portion of the discipline that concentrates on the geometry of the land scape (cf. spatial science). O?Sullivan and Unwin (2002) present spatial analysis as the study of the arrangements of points, lines, areas and surfaces on a map, and of their inter relationships. Analyses of those separate com ponents have deployed procedures adapted from other sciences nearest neighbour analysis and quadrat anaLysis, for point pattern anaLysis; graph theory for lines; and trend surface anaLysis for surfaces, for example. Whereas many geographers have undertaken analyses of the interrelationships using techniques from within the generaL Linear modeL, others have argued that spatial analysis poses particular statistical problems because of the nature of spatial data (cf. spatiaL autocorreLation), thus requiring special techniques. (NEW PARAGRAPH) The development of geographic informa tion systems is rapidly facilitating advances in spatial analysis and the greater power of com puters, together with software developments, has significantly increased geographers? ability to work with large and complex spatial data sets (cf. geocomputation). rj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Bailey and Gatrell (1995); Haining (1990). (NEW PARAGRAPH)
spatial autocorrelation
The presence of spatial pattern in a mapped variable due to geographical proximity. The most common form of spatial autocorrelation is where similar values for a variable (such as county income levels) tend to cluster together in adjacent observation units or regions, so that on aver age across the map the values for neighbours are more similar than would occur if the allo cation of values to observation units were the result of a purely random mechanism. This is positive spatial autocorrelation. Negative autocorrelation is where neighbouring regions are significantly dissimilar; more general and complicated forms of autocorrelation can also be defined. The presence of spatial autocorre lation is very widespread and indeed may be said to lie at the core of geography, as expressed in Tobler?s (1970) light hearted First Law of Geography: ?everything is related to everything else, but near things are more related than distant things?. (NEW PARAGRAPH) However, the presence of spatial auto correlation violates a basic assumption of independence in many standard statistical modeLs. Thus for regression, there is an assumption that the residuals are not autocor related. The issue of spatial autocorrelation was recognized early in the history of inferen tial statistics, but it was not until the work of Moran and Geary in the late 1940s and 1950s that tests were devised, and it was the devel opments by Cliff and Ord that brought the topic to prominence. A mathematical repre sentation of ?neighbours? was a stumbling block to computing the tests, and Cliff and Ord reformulated Moran?s test to employ a W matrix of size N x N, where N was the number of regions or observations, and a cell value wj of 1 indicated that regions i and j were neighbours, and 0 if they were not (Cliff and Ord, 1973). This idea opened up a whole field of research, and spatial autocorrelation is now a theme in many social sciences. Moreover, as Tobler?s Law suggests, spatial autocorrelation should not just be seen as a problem but also as a reflection of spatial interaction and a central aspect of spatial modelling, and this has been the basis for the development of spatiaL econometrics. The Moran test is a global one, detecting whether there is autocor relation on average across the set of regions; a more recent development has been the disag gregation of this measure into local measures, such as Anselin?s LISA (Local Indicators of Spatial Association) to detect local clusters of positive and negative autocorrelation (Anselin, (NEW PARAGRAPH) . (See also local statistics.) lwh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Odland (1988). (NEW PARAGRAPH)
spatial econometrics
An interdisciplinary research field being developed by economists, geographers and statisticians. The term was invented by Jean Paelinck (Paelinck and Klaassen, 1979), and the research focuses on the construction and application of statistical modeLs and tests explicitly designed for spatial (geographical) data, building on initial work on spatiaL autocorreLation by Cliff, Ord and others. (NEW PARAGRAPH) The field of econometrics was developed throughout the twentieth century by econo mists to deal with the special statistical mod elling issue posed by the non experimental context of economics and the social sciences, often very different from the Laboratory and agricultural field trials context for which much statistical theory was developed. In particular, econometricians constructed methods to deal with time series autocorrelation, time lags and dynamics in economic relationships and simultaneity and feedback between different equations in macroeconomic models. However, it is only in recent decades that equivalent techniques for spatial data have been developed. Amongst many contributors, (NEW PARAGRAPH) Luc Anselin?s work, and his computer package SpaceStat, have been particularly influential in developing both the methods and their appli cation. The focus of the field has moved from testing for spatial autocorrelation towards the modelling of spatiaL interaction through spatial diffusion, spatial lags or spillovers, and endogeneity is a major focus in the con struction of the estimators and tests. Lwh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Anselin (1988, 2002, 2003). (NEW PARAGRAPH)
spatial fetishism
Any approach that treats space as sufficiently autonomous to social pro cesses that ?no change in the social process or spatial relations could alter the fundamental structure of space? (Smith, 1981b, p. 112). The term was developed in the course of inter actions between human geography and marxism; by analogy with Marx?s critique of commodity fetishism, in which the conditions of production of a commodity are made invis ible and the economy is reduced to exchanges between objects rather than seen as a series of unfolding social relations and practices, so it was argued that approaches such as spatiaL science conceptualized space as somehow exogenous to and separate from social pro cesses (cf. Soja, 1980) (See also spatial separatism.) es (NEW PARAGRAPH)
spatial identity
The ways in which identities are constituted, articulated and contested in relation to space and pLace. A wide range of research has explored the territorialized spatialities of identity in relation to, for example, a region, ?homeland? or nation. Other research traces the deterritorial ized and reterritorialized spatiaLities of identity in terms of migration, diaspora and borderlands. Whilst some research has viewed space merely as a container for iden tity, or as a stage on which identities are played out, other research particularly since the 1990s traces the mutual constitution of both space and identity and their multiple and contested articulations (including Keith and Pile, 1993). Rather than view spatial identities in essentiaList terms, this research often inspired by post structuraLism, psycho anaLysis and post coLoniaLism traces their politicized differentiation. Although spatial metaphors have been particularly important in conceptualizing identity, geographers have been concerned to ground and locate the material spatialities of identity, which are often closely bound up with ideas about situated knowledge, the politics of location, and the spatial politics of identity (Yaeger, 1996; see also positionaLity). In a wide variety of con texts, geographical analyses of spatial identity thereby explore the metaphorical and material relationships between space, identity and power. (NEW PARAGRAPH) Post colonial and feminist theorists have been particularly influential in theorizing spa tial identity. In his classic work, Orientalism, Edward Said (2003 [1978]) explored the imaginative geographies of ?self? and ?other? through the intensely politicized spaces of the ?Orient?. Other post colonial theorists have explored the spatial identities bound up with migration, diaspora and the contested politics of hybridity, muLticuLturaLism and cosmopolitanism (including Hall, 1996a). In feminist theory, a frequently cited essay by Minnie Bruce Pratt (1984) traces her sense of identity through multiple spaces of home and memory. Other feminist theorists have theorized the interplay of gender and other identities in place, over space, and in shaping the production of space and knowledge. In her analysis of ?locational Feminism?, for example, Susan Stanford Friedman (1998) explores the critical interplay of space and identity through different discourses of positionality. As part of these discourses, ?situational approaches? not only ?assume that identity resists fixity, but they particularly stress how it shifts fluidly from setting to setting?, whereby ?[e]ach situ ation presumes a certain setting as site for the interplay of different axes of power and powerlessness? (p. 23). ab (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Friedman (1998); Hall (1996); Keith and Pile (1993); Pratt (1984). (NEW PARAGRAPH)

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