Geoscience Reference
In-Depth Information
1 Introduction
Over recent years accessibility has become one of the key questions discussed, not
only in the narrow context of transport geography research, but also in a broad
range of economic, social or planning studies. The possibilities that have emerged
resulted from increased computational capacity and the wide application of GIS-
software in accessibility studies and have provoked a growing number of studies
dedicated to transport geography issues. These increased possibilities permit the use
of more and more detailed geographical data prepared for wider study areas.
Nevertheless,
ection on the consequences for
accessibility analyses of the application of data designed at different spatial reso-
lutions. We still have limited knowledge about how models that are based on highly
disaggregated spatial data alter accessibility scale and pattern. The so-called
MAUP-effect (Modifiable Areal Unit Problem;[
1
]), broadly discussed in the spatial
studies literature [
2
there is a signi
cant
lack of re
fl
field of accessibility
studies. The existing investigations follow the approach of Townshend and Justice
[
6
], i.e. they concentrate on the selection of the resolution appropriate to the par-
ticular analysis focusing on the scale dimension of the MAUP [
7
,
8
]. At the same
time, they do not compare results between models that are based on administrative
units and grid layers. The paper presented here tries to bridge this gap, following
Fotheringham
5
], is still relatively undiscovered in the
-
s highlighting of the need for multiscalar spatial analysis [
2
]. We
used an assumption provided by Kwan and Weber [
9
], that the use of multilevel
modelling to explain accessibility offers the opportunity to
'
find geographical
variations previously invisible with single level models. Finally, the aim of the
paper is not only to provide evidence of the existence of the MAUP in accessibility
analysis (which is quite obvious), but also, following Wong [
10
], to highlight
locations that deserve more attention when applying the MAUP approach in
potential accessibility analysis.
The MAUP is a consequence of the use of arbitrarily de
ned boundaries of areal
units [
11
], i.e. the results of spatial analysis depend on the definition of the areal
units applied to the analysis [
3
]. The impact of MAUP can be divided into two
components: the scale effect and the zoning effect. The former is related to the level
of aggregation of spatial data, while the latter to the redrawing or regrouping of
spatial units at a given scale [
1
]. The difference between the units applied in the
study presented (i.e. municipalities and raster-cells) is linked to the scale effect of
the MAUP. The results of the accessibility study may be questioned when aggre-
gated data is used (e.g. municipal data), while no such criticism applies to an
investigation that is based on disaggregated data [
3
] or data that represents the
continuous space [
2
]. Herein, the raster layer consisting of 1 km
2
grid cells is used
as a proxy of disaggregated data that should be free from the MAUP effect. Due to
the smoothing process [
3
,
10
] an accessibility model that uses larger areal units (i.e.
municipalities) should provide a more homogenous surface for the spatial acces-
sibility pattern than a model that applies more detailed spatial units (i.e. raster-
cells). However, in addition to the scale of spatial units, the spatial aggregation
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