Geography Reference
In-Depth Information
ing the factors that actually lead to large numbers of zebra mussels. Some-
thing completely different may be causing the high number of zebra mussels.
Perhaps it is the size of lake, the number of boats using multiple lakes, or the
number of freeze-over days. In every case of geostatistics, the relationship
between the aggregation units and the things and events being studied must
be carefully examined.
Modifiable Areal Unit Problem
The modifiable areal unit problem (MAUP) is a special instance of the eco-
logical fallacy that results when data collected at a more detailed level of
aggregation—for example, census blocks, counties, or biotopes—are aggre-
gated to less-detailed levels of aggregation—for example, census tracts, states,
or watersheds. The aggregation units may be arbitrary to the things and
events being studied, but the aggregation units used in collecting or collat-
ing the data will affect the statistics that use this data. The consequences of
the MAUP can be significant. Although the assignment of counties to states
is political, statistics show that a switch of one northern Florida county to
Georgia or Alabama would have produced a different outcome in the 2000
U.S. presidential elections.
Terrain Analysis
Terrain analysis is an important application domain of geostatistics for a
number of disciplines and professions. Civil engineers rely on terrain analy-
sis when planning the construction of large structures, cellphone companies
use terrain analysis to plan the siting of antennas, city planners rely on ter-
rain analysis to assess the impacts of new buildings on the landscape, and
the military uses terrain analysis for planning and preparing missions. The
list could go on.
Because of the breadth of applications and the number of operations
and variables, the role of geostatistics in terrain analysis is hard to define. To
begin, you can distinguish types of terrain analysis by the role of visual inter-
pretation in the application. Some applications begin with a visual analysis of
field data, maps, aerial photographs, remote sensing images, or various com-
binations of these materials. Other applications may start out with
geostatistical analysis or rely on geostatistics to analyze the materials discov-
ered during a project.
For example, many archaeologists use terrain analysis by beginning with
a visual inspection of aerial photographs or remote sensing data to see if
traces of previous habitation or structures are visible. After comparing these
materials with previous archaeological projects and documents, the research-
ers often look to geostatistical techniques as a means of examining multiple
sources of data and evaluating characteristics in the data sources for relation-
ships that can help with understanding the previous cultures in an area. A
common application of geostatistics begins with analyzing previous habita-
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