ISLSCP II Global Population of the World

Global Population of the World (GPW) translates census population data to a latitude-longitude grid so that population data may be used in cross-disciplinary studies. There are three data files with this data set for the reference years 1990 and 1995. Over 127,000 administrative units and population counts were collected and integrated from various sources to create the gridded data. In brief, GPW was created using the following steps: * 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. * Additional population estimates were created by adjusting the source population data to match UN national population estimates for the reference years. * 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. * The resulting data were then transformed into grids of UN-adjusted and unadjusted population counts for the reference years. * 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.As with any global data set based on multiple data sources, the spatial and attribute precision of GPW is variable. The level of detail and accuracy, both in time and space, vary among the countries for which data were obtained.

全球人口数据集（GPW）将人口普查数据转换为经纬度网格，以便在跨学科研究中使用人口数据。本数据集包含三个数据文件，分别对应1990年和1995年的参考年份。通过整合来自不同来源的超过127,000个行政单位和人口计数数据，构建了网格化数据。概而言之，GPW的创建过程如下：
* 对产品参考年份，即1990年和1995年，的人口数据进行估算，该估算可通过数据源直接得出，或通过插值或外推其他年份的估算值获得。
* 通过调整源人口数据，以匹配联合国对参考年份的国家人口估算，创建了额外的估算。
* 当适当时，将空间数据的边界和海岸线与《世界数字海图》进行匹配，并添加了《世界数字海图》中的湖泊。
* 将得到的数据转换为包含参考年份联合国调整后和未调整的人口计数的网格。
* 创建包含每个单元格内行政边界数据面积（扣除湖泊后）的网格，并与计数网格一起使用，以生成人口密度。鉴于任何基于多个数据源的全球数据集，GPW的空间和属性精度均有差异。时间和空间上的详细程度及准确性在获取数据的国家之间存在变化。