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in west-central Africa, Central America, eastern North America, and Europe.
Australia, the northern latitudes of Asia and North America, and north Africa
stand out as the least densely populated. The reasons for the patterns are
many, but they include historical settlement, climate, sustainable agriculture,
ocean and land trading routes, and terrain.
Click on the 1990 population data layer and compare the 1990 data to the
2015 estimates, first by examining the region along the border between
France and Germany from 1990 through 2015, and then northern Nigeria
for the same time period. What demographic variables account for the
larger increase in Nigeria versus that of France? The demography of Nigeria
includes a much younger population and a correspondingly lower median
age than that of France, resulting in a higher growth rate. Pan and zoom
the map back to the France-Germany border. Do you think the population
density really is that much higher in Germany versus that of France, or is
this just an artifact due to the larger aggregations of the data collection units
in Germany? As we have stated throughout this topic, be critical of the data.
Just because the data are shown on a single map does not mean that all the
data came from the same source. Indeed, the Gridded Population Map of the
World is highly dependent on the size of the administrative unit that was
used as an input.
According to a variety of outside sources, Germany does have roughly twice
the population density as does France (235 people per square kilometer
for Germany versus 108 for France). But the map seems to indicate that
broad areas of Germany are even higher in density, approaching that of the
Netherlands. Is this accurate? Upon further investigation into the metadata,
indeed, the resolution of the data set was to blame. CIESIN uses the highest-
resolution data available for generating maps like this, and the data they
were able to obtain for France had a much higher resolution. The resolution
is calculated as the square root of the land area divided by the number of
administrative units. For Germany, it was 28, and for France, it was four.
The resulting population per administrative unit in 2000 was 184,000 for
Germany versus only 2000 for France. Fortunately, CIESIN does an extremely
good job documenting their sources and methods. The user still needs to
make it a point to read that documentation. But what should we do when
working with sites that do not document their data well? In today's world of
myriad data, maps, and tools, it is more important than ever to have a good
grounding in map interpretation and spatial analysis, but also to ask ques-
tions of the data you are using.
Under the map, use the population estimation service. Draw a polygon on
the resulting map and obtain the total area and population for the polygon
you drew. On the basis of the information in this chapter describing how
the data were generated, how much confidence can you place in the popu-
lation estimate? Do you think that the estimates vary in quality depending
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