Thanks to everyone who responded about catchment areas, I thought it might
be useful to summarise for the list as many of the replies were direct to
me.
Firstly there is no common definition ("Ours are 'made up' too!") although
we are all using roughly the same idea best summarised by Peter Marshall
from Bexley: "a) The catchment area of library A is that area from which
users habitually travel to visit library A. or b) The catchment area of
library A is that area from which more users travel to visit library A than
to visit library B, library C, etc"
The replies fell into 2 camps those with their own GIS & those like myself
who have to rely on another section of their authority for any GIS work.
Even with GISs we can have the problem of creating "some sort of zoning of
diminishing percentages of use, and only attribute customers to a library
if active borrowers constitute more than (X)% of the population of a
postcode (or combination) ?" (Andrew Sandeman, Edinburgh).
It is at this stage we have to move to some sort of intuitive decision for
cut off points as does Fred Miller (North Tyneside) based on a GIS map "a
pragmatic definition of the natural catchment area for this library (just
about our smallest) would be the dense cluster around the library, complete
with northward pointing outlying arm". It is perhaps these arms & the dents
which make catchments such odd shapes that keeps it less than a science.
The problems of overlap, small libraries totally within a larger library's
area, the effects of central libraries, workplaces of users & transport
routes all came up in the correspondence.
John Usher (Islington) gave details of "just a pilot" but it was clear from
his description of how they'd used their GIS that they are further along in
developing their solutions to these problems than most of the rest of us.
Also at another level I wonder how much further we have come from the
Bexley coloured dots on a map, until we become much better with GIS systems
we are merely doing the same thing in a less labour intensive way.
Lionel Aldridge
Performance Manager
Leeds Library & Information Services
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