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WorldPop gridded datasets are provided in geotiff format. This data format is readable by all Geographical Information System software types, including ArcGIS, QGIS, MapInfo, SagaGIS and many others. Additionally, many datasets are provided in comma-separated values (csv), and our apps and portals enable exploration and interaction with the datasets for those without GIS or programming skills.

To learn how WorldPop converts census data into gridded estimates, please see our methods page, case study pages and publications page

WorldPop integrate many different types of geospatial data in building demographic datasets, ranging from satellite, survey, census, cellphone and many other sources. Please see our methods page, case study pages and publications page for more details.

Different coordinate reference systems (CRS) are employed for different countries, and for different types of data. Country-level datasets presenting ‘People per hectare’ (pph) values are mapped in a suitable country-level map projection, typically UTM (Universal Transverse Mercator) or occasionally a specific country grid. Datasets presenting ‘People per pixel’ (ppp) values are not projected; they are mapped to a global geographic coordinate system, GCS_WGS_84.

Yes, detailed descriptions of the methods and improvements made in the WorldPop data collection are described in the papers found on the publications page.

A variety of WorldPop datasets exist to meet differing needs, and many have arisen through specific projects supporting governments or UN agencies, among others. This leads to variations in methods, outputs and documentation in some cases. 

We are constantly updating existing datasets and posting new ones that arise from research and projects. You can keep updated on these through following us on Twitter (@WorldPopProject) or LinkedIn (search for WorldPop). You can also read about new projects and upcoming datasets on our news and projects pages.

WorldPop datasets are updated when new census or geospatial datasets are available, or for specific stakeholder needs. The date of production of each dataset is provided on the dataset download page and the source and date of input datasets are provided in metadata files and on the methods page.

WorldPop datasets have been downloaded and used by researchers and policy makers based in governments of every low income and lower-middle income country in Africa, Asia and the Americas, supporting development, health and planning. Moreover, WorldPop provides the default subnational population data for all UN agencies, the data that feeds into the DHIS2 health information software used by more than 70 ministries of health covering 2.4 billion people, and the basis for UN estimates of populations affected by disasters and conflicts. The data are also the demographic basis for many health applications, including active use by governments for childhood vaccine delivery, and the Imperial College London and University of Washington COVID-19 models that prompted UK and US national lockdowns. See the case studies, about worldpop, and publications page for further details.

The United Nations produce their own estimates of national population totals that take into account a range of factors. These estimates can sometimes differ from the totals obtained in national censuses and used by governments. We therefore produce two versions of our population datasets: (i) adjusted nationally to match census totals and (ii) adjusted nationally to match UN estimates. This provides flexibility to users to choose which numbers are most appropriate for their analyses.

Regarding how to map the data, for each country of interest, I would suggest to use the ArcGIS “XY To Line” tool after adding a “GEONAMEID” field to the corresponding migration csv table available here:

http://www.worldpop.org.uk/geodata/summary?id=1281
http://www.worldpop.org.uk/geodata/summary?id=1282
http://www.worldpop.org.uk/geodata/summary?id=1283

The “GEONAMEID” field can then be used to join the “PrdMIG” information to the attribute table of the corresponding flowline dataset produced using the “XY To Line” tool – additional hints on how to create flow maps with ArcGIS can be found here:

https://blogs.esri.com/esri/arcgis/2011/09/06/creating-radial-flow-maps-with-arcgis/

For all datasets, please cite the WorldPop website as the source: www.worldpop.org. When downloading each dataset, a recommended citation is provided, as well as a doi for the dataset.