The Dictionary of Human Geography (184 page)

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Authors: Michael Watts

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shift-share model
A technique for describ ing the relative importance of different components of growth/decline in a regional economy, widely used in regional science. Growth may be due to a region having a high concentration of industries that are growing nationally, for example; because of locational shifts within certain industries towards that region; or because of differential regional trends within and across industries. Shift share analysis splits a region?s growth (in employment, for example), relative to the national norm, into: (a) a proportionality (NEW PARAGRAPH) shift, that proportion of the growth (decline) associated with the concentration of relatively fast(slow) growing industrial sectors there; and (b) a differential shift, that proportion ref lecting local trends that deviate from the national. rj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Armstrong and Taylor (1978). (NEW PARAGRAPH)
shifting cultivation
Minimally, shifting cul tivation is an agricultural system characterized by a rotation of fields rather than of crops, by discontinuous cropping in which periods of fallowing are typically longer than periods of cropping, and by the clearing of fields (usually called swiddens) through the use of slash and burn techniques. Known by a var iety of terms (including field forest rotation, (NEW PARAGRAPH) slash and burn, and swiddening), shifting cultivation is widespread throughout the humid tropics, but was also practiced in tem perate europe until the nineteenth century (and sometimes later) (Conklin, 1962). It is estimated that there are over 250 million shift ing cultivators world wide, with 100 million in South East Asia alone. Shifting cultivation is enormously heterogeneous and subtypes can be distinguished according to crops rai sed, crop associations and successions, fallow lengths, climatic and soil conditions, field technologies, soil treatment and the mobility of settlement. Many distinguish between inte gral (shifting cultivation as an integral part of subsistence) and partial (shifting cultivation as a technological expedient for cash cropping; see peasant) forms of shifting cultivation (Conklin, 1962). In all shifting cultivation systems, the burning of cleared vegetation is critical to the release of nutrients, which ensures field productivity. Shifting cultivation by definition is land extensive, and is threa tened by population growth and migration, and expanding land occupation (see carrying capacity; intensive agriculture). Shifting cultivation is often stigmatized as primitive or unproductive, but it is typically predicated upon a sophisticated understanding of local environmental conditions so called indigen ous knowledge and exhibits considerable flexibility and adaptiveness. mw (NEW PARAGRAPH)
significance test
A statistical procedure for identifying the probability that an observed event could have occurred by chance. Most statistics such as a correlation coefficient have an associated sampling distribution identifying all possible values of the coefficient for a given set of empirical observations. For example, three observations can be rank ordered in six different ways, so that if one is correlating the rank order of neighbourhood death rates with the local levels of lead pollu tion, there would be 36 different ways in which the two sets of three observations could be organized, each producing a different correl ation coefficient. Those coefficients form a frequency distribution in which some val ues would appear quite frequently, others more rarely. If the observed coefficient?s value would occur only rarely, this outcome was unlikely to occur by chance: it is then pre sented as a significant result, as a correlation with interpretative value. (NEW PARAGRAPH) In studies involving large numbers of obser vations 80 neighbourhoods instead of three, say the frequency distribution can be predetermined and the observed statistic located within it. Most analysts operate the rule of thumb that if an observed outcome is likely to occur less frequently than five times in every 100 ways in which the data can be organized, that is a statistically significant result. Statistical significance should not be confused with substantive importance, how ever; it says nothing about the importance of findings and how they should be interpreted. (NEW PARAGRAPH) Statistical significance tests are used in two ways. In confirmatory data analysis, they assist hypothesis testing, indicating whether an observed outcome in a sample (see sam pling) is likely to characterize the population from which it was drawn. (If the 80 neigh bourhoods were a sample from 240 within a city, a correlation coefficient statistically significant at the 0.05 level would indicate that the relationship between the two variables in the sampled areas would almost certainly be found if the whole population had been studied.) In exploratory data analysis, there is no sample involved and the test is used to indicate the likely importance of an observed relationship occurring: one that would occur three times in every ten ways in which the data are organized is probably less important than one that would occur only once in every 500 ways. rj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Blalock (1970). See alsohttp://bowland files.lancs. ac.uk/monkey/ihe/linguistics/corpus3/3sig.htm. (NEW PARAGRAPH)
simulacrum
A term originally derived from Platonic theory, but popularized by Jean Baudrillard. Literally, the simulacrum is a copy without an original. Baudrillard extended the argument about the modern dominance of images and ideology by suggesting an histor ical procession of the simulacra. First, there was presence people met and spoke then tech nologies of writing allowed re presentation of those who were not present. Now media allow the simulation of those who never existed. The term gained wide usage in discussions of themed environments such as Disneyland or shopping malls. ?Main street?, Disneyland thus simulates a mythic idea of a small town community hub that has no counterpoint in reality (see disneyfication). mc (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Baudrillard (1983). (NEW PARAGRAPH)
simulation
A heuristic device for solving otherwise intractable mathematical and statistical problems. There are two broad types of application: the creation of ?artificial worlds?, and the use of simulation as part of the estimation of quantitative models. An early application of the former was Torsten Hagerstrand?s work on the diffusion of innovation. He treated this as a spatial sto chastic process, in that while it had an underlying structure (adoption would decrease with distance as social interaction decreases) it could also turn out differently each time. Monte Carlo procedures were used to draw random numbers and innovation dif fused outwards from initial adopters according to a probabilistic mean information field. Such simulation has grown rapidly in recent years and it is at the core of micro simulation methods and agent based modelling. Such approaches have now developed to the extent of the SimBritain project, where as part of evidence based policy the geographical impact of government policies can be evalu ated (Ballas, Clarke, Dorling and Rossiter, 2007). (NEW PARAGRAPH) The second use of simulation, statistical model calibration, has also seen major recent developments, which have been considerably aided by increased computing power. One aspect of this is a computer intensive appro ach to confirmatory data analysis and hypothesis testing, in which the observed data are re sampled to characterize the empir ical distribution of a test statistic. More importantly, a new method of estimation called markov chain Monte Carlo simulation has been developed that allows the estimation of very complex models, including multi level models. This methodology allows a building block approach to estimation, so that complex problems can be decomposed into lots of small ones. It is especially important for bayesian analysis, for it allows the estima tion of previously intractable joint posterior distribution (based on prior beliefs, data and assumptions) by iterative simulation from the much more straightforward marginal distribu tions (Davies Withers, 2002). kj (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Gilbert and Troitzsch (2005); Gill (2002); Noreen (1989). (NEW PARAGRAPH)
situated knowledge
A term coined by the feminist cultural critic of science, Donna Haraway (1991, p. 188), to denote ?a doctrine of embodied objectivity that accommodates paradoxical and critical feminist science pro jects?. Situated knowledge replaces the traditional conception of science as the pur suit of a disembodied, inviolable and neutral objectivity with a formulation of objectivity that stresses corporeality, social construc tion and cultural politics. (NEW PARAGRAPH) Haraway argues that vision or sight is a guiding metaphor for Western scientists in carrying out their work: they see the world, they make observations and collect evidence (from the Latin verb, videre, to see) and they write down its truths. This conceit carries over into ordinary speech too when we say, for example, ?I see?, meaning ?I understand?. The language of knowledge production is saturated with visual metaphors in both a technical scientific and an everyday sense. But Wittgenstein reminds us that ?the limits of my language are the limits of my world?, and in working within this language, in construing vision and visuality in this way, scientists limit their worlds by writing themselves out of their own stories: failing to recognize their constitutive role in world making, they reduce themselves to the status of ?modest witness? (Haraway, 1997, ch. 1). That presumption of modesty, Haraway argues, is a direct conse quence of the starting point of visuality. It creates the illusory possibility of a disembod ied science. She calls this illusion a ?god trick?, the idea that it is possible to have ?vision from everywhere and nowhere? (Haraway, 1991, p. 191). Moreover, it is just such a trick that is the basis of one of science?s most cherished ideas, objectivity, the belief in the possibility of a single, final, detached and unmarked order ing of the world. For Haraway (1991, p. 188), however, the ?gaze from nowhere?, as she calls objectivity, is really a rhetorical move that hides and protects the interests of those who propose and benefit most from it, typically white Western men. ?Modesty pays off . . . in the coin of epistemological and social power? (Haraway 1997, p. 23: see also epistemol ogy). In this sense, then, being a ?modest witness? turns out not to be very modest at all. It is a strategy to promulgate a particular kind of knowledge and to guarantee its unassailable truth, which is often indelibly marked by heteronormativity, masculinism and racism (as her case studies from the life sciences testify). (NEW PARAGRAPH) Haraway (1997, ch. 4) labels scientific practices that masquerade under the cloak of objectivity ?fetishistic? because such know ledge is represented as a thing rather than a social process. Fetishism would not occur if it were recognized from the outset that all knowledge is embodied and partial; that is, ?situated?. And with that recognition comes the possibility of ?a usable, but not an innocent doctrine of objectivity? (Haraway, 1991c, p. 189). This form of ?usable objectivity? depends upon the two terms that underpin it: (NEW PARAGRAPH) Embodiment means recognizing that knowledge is produced by specific bodies that always leave traces. Moreover, em bodiment is not only human but also ?machinic?. Machines see and record the world and, like humans, they are more than passive observers; they con struct it on the basis of particular algo rithms and assumptions (cf. actor network theory). For example, soft ware used in the computer programs of geographical information systems brings a systematic set of biases, hidden assumptions and aporias. Printouts and screenshots are not mirror copies of the world, ?the view from nowhere? but al ways the view from somewhere. Further, embodiment is collective not singular, mobile not fixed. Haraway (1991, p.195) writes: ?feminist embodiment (NEW PARAGRAPH) . . . is not about fixed location in a reified body . . . but about nodes in fields, in flections in orientations, and responsibil ity for differences in material semiotic fields of meaning?. Haraway?s objectivity is constantly in motion, tugged and pulled among the various nodes of its constitutive field. (NEW PARAGRAPH) Partial knowledge implies a recognition that no one, except gods and goddesses, possess full (objective) knowledge. There are only partial perspectives, a conse quence of our own circumscribed subject location that makes us who we are, and what we know. Haraway (1991, p.193) writes: ?the knowing self is partial in all its guises, never finished, whole, simply there and original; it is always constructed and stitched together imperfectly.? (NEW PARAGRAPH) Embodiment and partiality are the condi tions under which knowledge is acquired. Only when they are recognized as such is there hope of an attainable as opposed to a mythical objectivity. These are also the conditions of any politics. Embodied and partial knowledge necessitates that people literally reach out to one another and construct networks of affili ation: that is, they must engage in discussion, deliberation and evaluation; they thus come to recognize difference but also common beliefs and shared responsibilities. Through these ?shared conversations in epistemology?, Haraway (1991, p. 191) argues, it is possible to forge ?solidarity in politics?. This does not mean that the end result is unanimity, or even that networks and conversations set us on a collective trajectory towards some final agree ment. To the contrary, that was the assumption (and the failure) of the old type of objectivity. Rather, ?shared conversations? are open ended, varied, sometimes inconsistent and paradox ical. But they are all we have, and the necessary condition for both political projects, such as feminism, and epistemological ones, such as science. As a result, the traditional notion of objectivity must be recast, conceived as an incomplete process, not a final outcome. Objectivity then becomes the process of work ing out difference and commonality, of strug gling epistemologically and politically to make connections, affiliations, and alliances. While situated knowledge is often contradictory, it contains the possibility of critical promise. (NEW PARAGRAPH) It is in exactly this spirit that Gregory (NEW PARAGRAPH) argues that visions of modern geog raphy as an intrinsically European science whose origins can be traced back to the late eighteenth century, and in particular to scien tific expeditions beyond the shores of europe (see exploration), mask its genealogy as a distinctively Eurocentric science. Geographical knowledges, like any others, are always situ ated knowledges: their production often (NEW PARAGRAPH) involves travel, like Cook?s voyages into the South Pacific or the orbits of Earth sensing satellites through space, and the products themselves enter into complex circuits of exchange, transfer and accumulation, but they are always marked by the situations in which and through which they are constituted (see also ethnocentrism; eurocentrism; orientalism). Merrifield (1995) treats quite other, more recent and more radical ?exped itions? as exercises in the production of situ ated knowledge, while Cook (2001a, 2004) has used Haraway?s proposals as a research method, a pedagogy, a form of writing and an exploration of material culture. In all these cases, however, it is important not to confuse situated knowledge with a form of ideology critique that subscribes to quite traditional notions of objectivity. For, as Rose (1997b) emphasizes, anyone claiming to fully situate their own knowledge is practising pre cisely the same kind of god trick that they criticize in others. All situated knowledge is partial, including the situated knowledge we have of ourselves and, of course, every entry in this Dictionary (cf. local knowledge). tb (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Haraway (1991, ch. 9). (NEW PARAGRAPH)

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