People, spaces and places - The Visualization of Spatial Social Structure - page 52

should look similar to each other despite the arbitrary local boundaries that differ
between them.
For detailed social mapping to work, the most important factor about the
localities that we use is that they vary little in the number of people that they
contain. This is because larger areas tend to give a false sense of more uniformity
within them. Again we require equal representation of people as a means to reduce
the arbitrariness of the visualization. If you try to make sure that you give all
people equal weight and don't draw graphics that place too much emphasis on a
few, then you are less likely to become distracted by patterns that are arbitrary.
During the 1980s, at the same time as 'functional' regions were being created,
other researchers were turning their hand to placing lattices over the land area of
the British Isles and counting attributes of the number of people in each small
square. This method of division was called grid mapping, and one kilometre
squares were most often used.
Grid mapping is no less arbitrary a practice than any other technique, although
the practicalities of its execution are the simplest. That it creates a stable set of
units over time is a trivial defence of the method; any set of lines you draw and
leave on a map is 'stable'. This type of spatial division can be seen as flawed for
the visualization of human geography, partly because of the huge inequalities in
populations located within the small unfamiliar areas it creates. 11
Today a very fine population grid can be used and there is enough spare com-
puting capacity not to worry that almost all the grid squares contain no people.
Two decades ago computers were not so powerful, which was useful because
it made you think more carefully about what you really wanted to do and see.
What if you wanted to see roughly ten thousand to one hundred thousand
localities across all of Britain? Fortunately, the lowest tier of administrative
geography gave and still gives us the first set - wards - and that of census geog-
raphy the second - enumeration districts. There are other practical alternatives,
for example postcode sectors, on which much market research is based, num-
ber over eight thousand (Figures 2.13, 2.14 and 2.15). However, in general the
absolute wealth of information that is available at the time of the census for
enumeration districts 12 and for wards between census years makes these places
the natural choices from which to start painting spaces.

2.6 Population space

We d o ' ... . high-pass filtering in our “mind's eye”.'

(Tobler, 1989b, p. 19)

11 'More than this unfamiliarity though, is the deep-seated, if irrational, feeling that they are
distinctly “unnatural”, while “anything which wiggles” is “natural”' (Rhind, 1975a, p. 3).
12 In more recent years census data have been disseminated by 'output areas', which differ a
little in shape and size from the areas used to enumerate, but can be considered as largely equivalent
here. They differ in being optimised to be more homogeneous, following the advice of Professor
David Martin.