The Dictionary of Human Geography

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computing power much more complex models

can be run, which continue to provide the

somewhat counter-intuitive result that segre-

gation is greater than people’s individual pref-

erences suggest (Fossett, 2006).

Agent-based modelling is widely used in the

social sciences – in, for example, modelling the

spread of diseases (cf.epidemiology), traffic-

generation, land use and land cover

change, thediffusionof ideas,migration,

crowding in small spaces and inter-firm com-

petition (see http://www.econ.iastate.edu/

tesfatsi/ace.htm). rj

Suggested reading

Batty (2005); Testfatsion and Judd (2006).

agglomeration The association of product-

ive activities in close proximity to one another.

Agglomeration typically gives rise toexternal

economiesassociated with the collective use of

theinfrastructure of transportation, com-

munication facilities and other services.

Historically, there has been a tendency for eco-

nomic activity to concentrate spatially, the large

markets associatedwithmetropolitanareasadd-

ing to the external cost advantages. Agglomer-

ation also facilitates the rapid circulation of

capital, commodities and labour. In some cir-

cumstances,decentralization may counter

agglomerative tendencies; for example, if land

costs and those associated with congestion in the

central area are very high. (See alsoeconomies

of scale;economies of scope.) dms

Suggested reading

Malmberg (1996); Scott (2006).

aggregate travel model A statement, often

expressed as an equation, that predicts some

aspect of travel (e.g. the number of trips or

travel mode) for units (e.g. individuals or

households) aggregated to small areas, often

called ‘traffic analysis zones’. The data are

collected and analysed for these zones, obscur-

ing differences that may exist within zones

and, because zones do not make travel de-

cisions, rendering impossible investigation of

decision-making processes underlying travel.

For example, number of trips generated by a

zone may be predicted as a function of the

zone’s average household income and average

number of vehicles per household. Aggregate

travel models have been fundamental to trans-

portation planning since the 1950s. sha

Suggested reading

Hanson (1995, esp. chs 1,4,5,6).

agrarian question The forms in which cap-

italist relations transform the agrarian sector,

and the political alliances, struggles and com-

promises that emerge around different trajec-

tories of agrarian change. The founding

theoretical text in studies of the agrarian ques-

tion is Karl Kautsky’sThe agrarian question,

first published 1899 (but not translated into

English until the 1980s). Kautsky’s focus on

the agrarian question in western Europe rested

on a striking paradox: agriculture (and the

rural) came to assume a political gravity pre-

cisely at a moment when its weight in the

economy was waning. Agriculture’s curious

political and strategic significance was framed

by two key processes: the first was the growth

and integration of a world market in agricul-

tural commodities (especiallystaples) and the

international competition that was its hand-

maiden; and the second was the birth and

extension into the countryside of various forms

of parliamentary democracy. International

competition in grains was driven not only by

the extension of the agriculturalfrontierin

the USA, in Argentina, in Russia and in east-

ern Europe (what Kautsky called the ‘col-

onies’ and the ‘Oriental despotisms’), but

also by improvements in long-distance ship-

ping, by changes in taste (e.g. from rye to

wheat) and by the inability of domestic grain

production to keep up with demand. As a

consequence of massive new supplies, grain

prices (and rents and profits) fell more or less

steadily from the mid-1870s to 1896 (Konig,

1994). It was precisely during the last quarter

of the nineteenth century when a series of

protectionist and tariffpolicies in France

(1885), Germany (1879) and elsewhere were

implemented to insulate the farming sector.

New World grain exports were but one expres-

sion of the headlong integration of world com-

modity and capital markets on a scale and with

an intensity then without precedent and, some

would suggest, unrivalled since that period.

Kautsky then devoted much time to the

Prussian Junkers and their efforts to protect

their farm interests. But in reality the structure

of protection only biased the composition of

production in favour of grains (and rye in

particular) grown on the East Elbian estates.

Tariffs provided limited insulation in the pro-

tectionist countries, while the likes of England,

The Netherlands and Denmark actually

adopted freetrade(Konig, 1994). Protection

did not, and could not, save landlordism but

was, rather, a limited buffer for a newly en-

franchised peasant agriculture threatened

by the world market. The competition from

Gregory / The Dictionary of Human Geography 9781405132879_4_A Final Proof page 14 31.3.2009 9:44pm

AGGLOMERATION