Cobweb of flows - The Visualization of Spatial Social Structure - page 165

6

Cobweb of flows

Look upon the population and its various activities as a part of a
vertically-rising stream in space-time with oblique tributaries of move-
ments in a short chronological perspective and a longer one (for
example, daily journeys to work and migratory moves respectively).
(Szeg o, 1987, p. 200)

6.1 What flow is

Flow is more than change. It describes the static structure of change: how the
change came to be, what changed. Change is a difference; flow is an entity
in itself. It is of an order of complexity above change and involves a quantity
of information of an entire order of magnitude greater than change (something
reflected in the file sizes of the images shown). In our social structures it is the
movement between places, rather than alterations within them, that are respon-
sible for the restructuring we see.
To paint a picture of the static social structure at any point in time, we
need only know the situation in each cell of the structure. To show where that
structure is changing we need to know the situation around at least two points
in time for every cell. To show how that structure changed, what moved from
where to where, information is required about the relationships between all cells
(Box 6.1). Flows are real. The people they measure did move from one place to
another (Figure 6.1). This is the structure of change, the structure of movement.
It forms a cobweb that links places. 1

1 Most census mapping is of the distribution of night-time population: 'This effect, which some-
times distorts at least some aspects of city life, can be overcome in some degree by measuring
changes over time and movements in space; the static structure is only a departing point for the
analysis of a living city' (Shepherd, Westaway and Lee, 1974, p. 112).

The Visualization of Spatial Social Structure , First Edition. Daniel Dorling.

2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.