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Download a working
paper that documents how GPW was produced and describes key results
from analysis of the dataset.
Source Data
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View details on the input data, including data sources,
images of the boundary data and population adjustments applied to
the data. See the summary table or link
from there to information for individual countries.
Methodology
Details on the methodology are explained in full in the working
paper. In brief, GPW was created by linking population estimates
for national and sub-national units to vector boundary data using
the following steps:
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Population data were estimated for the product reference
years, 1990 and 1995, either by the data source or by interpolating
or extrapolating the given estimates for other years.
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Additional population estimates were created by
adjusting the source population data to match United Nations (UN)
national population estimates for the reference years.
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Borders and coastlines of the spatial data were
matched to the Digital Chart of the World where appropriate and
lakes from the Digital Chart of the World were added.
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The resulting data were then transformed into grids
of UN-adjusted and unadjusted population counts for the reference
years.
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Lastly, grids containing the area of administrative
boundary data in each cell (net of lakes) were created and used
with the count grids to produce population densities.
Accuracy and Precision
As with any global data set based on multiple data sources, the spatial
and attribute precision of GPW is variable. Factors, discussed at
length in the working paper, that
contribute to the varying precision and accuracy of GPW include:
Applications of GPW
GPW has potential for many different applications, especially in
interdisciplinary studies of the environment. Some examples of how
GPW has been used are available in the list of publications
or in the working
paper.
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