The Dictionary of Human Geography

Trading Systems (LETS) is evidence of this
(seealternative economics). So too is the
growth of gardening and maid services in
cities such as Miami and Los Angeles in the
USA, largely staffed by labourers from Latin
America. sco

Suggested reading
Roberts (1994); Tripp (1997).

information economy A term dating from
the late 1960s and early 1970s, describing the
growing centrality of information to thede-
velopmentandrestructuringof advanced
industrial economies. Pioneering work by
sociologist Daniel Bell (1973) outlined the
increasing significance of the distribution,
production and consumption of information
within what he calledpost-industrial soci-
ety. Since then, human geographers –
amongst many others – have made major
contributions to understanding the spatial
dynamics of information-intensive industries
(Hepworth, 1989) and the highly uneven
geographies of computer networks such as
the Internet that integrate information econ-
omies (Zook, 2005: see also knowledge
economy;learning region). sg

Suggested reading
Hepworth (1989).

information theory A mathematical ap-
proach originally developed in communication
science to measure the amount of information,
degree of organization oruncertaintyin a
system. The measure is closely related to
that forentropy. The basic equation devel-
oped by Shannon (Shannon and Weaver,
1949) is as follows:

H¼

X

i

pilog (1=pi),

whereHis the information statistic andpiis
the probability (or proportion) of a variable in
a given region. The individualpis might be
employment in different regions, the propor-
tion of agricultural land inNcounties or the
probabilities ofNpossible outcomes in a sto-
chastic experiment.H¼0 when one of thepiis
unity – all the employment is concentrated in
one region – whilstHapproaches a maximum
(given by logN) when all thepiare equal.H
is perfectly related to log W, the entropy
measure. Information theory was extensively
applied to the measurement of social and
economic inequality by Henri Theil

(Theil, 1967). In geography, it has been used

to measure organization in settlement patterns,

information in choropleth mapping tech-

niques and in regional classification, as well

as in the applications involving entropy-

maximizing models. lwh

informational city A term coined by

Manuel Castells (1989) to describe acity

whose development is dominated by the re-

structuring dynamics of manufacturing and

research and development (R&D) in ‘hi-tech’

industries (primarily information technology,

defence, biotechnology and nanotechnology).

Based on a detailed analysis of urban change

in the USA in the late twentieth century,

Castells suggested that such developments

were underpinning the emergence of a global

urban systemmade up ofworld citiesdom-

inated by centralized clusters of innovation in

these high-technology sectors. He argued that

these sectors were located in suburban com-

plexes calledtechnopoles, which tended to be

associated with increasingly dualized social

structures and the dismantling of welfare

state systems (Castells and Hall, 1994). sg

Suggested reading

Castells (1989).

infrastructure In conventional economic

theory and planning, infrastructure refers to

the underlying structure of services and amen-

ities (social overhead capital, or SOC) needed to

facilitatedirectly productive activity(or DPA).

Examples include public services,transport,

telecommunications, public utilities, and so-

cial and community facilities. Infrastructure

tends to be immobile, labour intensive,

indivisible and open of access, and to have

economy-wide effects. There is considerable

argument over the extent to which infrastruc-

tural investment is a sufficient or even a neces-

sary precondition for economic development;

whether it should be provided before develop-

ment in the form of excess capacity or whether

scarce resources should be devoted primarily

to DPA; and whether it should be publicly or

privately owned. Indeed, the widespread

growth of the private ownership of infrastruc-

ture and its ability to generate stable returns

over long periods has led to significant finan-

cial interests in infrastructural development,

not just in terms of ownership and financing,

but as the basis of a range of disintermediated

financial instruments.

Withinmarxism, ‘infrastructure’ has a more

precise and theoretically charged meaning.

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INFORMATION ECONOMY