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The Impact of Data Aggregation
on Potential Accessibility Values
Marcin St
pniak and Piotr Rosik
ę
Abstract The paper focuses on an investigation of the Modi
ed Areal Unit
Problem (MAUP) in a potential accessibility case study of the Mazovia region.
Three different potential accessibility models were prepared based on the same
theoretical background and coherent spatial data: a municipal model, a grid model
and a population-weighted average travel time model. We concentrated on two
main issues: the differences in the results produced by the three different models,
and the impact of different methods of calculation of self-potential on these dif-
ferences. The results show signi
cant differences in accessibility values produced
by the three models tested. The municipal model produced underestimated values
of potential accessibility indicator in all spatial units. The differences are
first of all
a consequence of taking into consideration the densely populated peripheral dis-
tricts of Warsaw that are
'
'
'
'
(i.e.
averaged) in the central-location oriented municipal model. As a consequence, the
total travel time between the average (population-weighted) origin-destination grid
nodes is shorter than that calculated at the municipal level and the potential
accessibility values are higher in both grid-based models. However, in general, the
main cause of the differences of accessibility values observed is not the self-
potential but rather the complexity of transportation and land use relations between
neighbouring municipalities.
visible
in grid-based models, but
not visible
Keywords Potential accessibility
Modi
able areal unit problem
Self-potential
Poland
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