While summary national-level statistics from sources such as the World Bank are a useful tool, these national-level figures may conceal great heterogeneity across subnational units such as provinces and large urban areas. Such differences are displayed in the figures below, with data on the percentage of stunted children under age 5, nationally and by region within countries. For example, while 40 to 50 percent of Tanzanian children overall are stunted, the figures range from under 20 percent to 50 percent or more across Tanzanian regions.
The Demographic and Health Survey program is continually collecting and releasing new data; at this writing, nineteen countries are collecting or processing data for standard DHS surveys. Researchers want the latest data for countries of interest, as soon as those data become available. To minimize the wait between the original DHS data release and the release of integrated data, IPUMS DHS is now releasing data multiple times a year.