Sub-national mapping of population pyramids and dependency ratios in Africa and Asia

Abstract

The age group composition of populations varies substantially across continents and within countries, and is linked to levels of development, health status and poverty. The subnational variability in the shape of the population pyramid as well as the respective dependency ratio are reflective of the different levels of development of a country and are drivers for a country's economic prospects and health burdens. Whether measured as the ratio between those of working age and those young and old who are dependent upon them, or through separate young and old-age metrics, dependency ratios are often highly heterogeneous between and within countries. Assessments of subnational dependency ratio and age structure patterns have been undertaken for specific countries and across high income regions, but to a lesser extent across the low income regions. In the framework of the WorldPop Project, through the assembly of over 100 million records across 6,389 subnational administrative units, subnational dependency ratio and high resolution gridded age/sex group datasets were produced for 87 countries in Africa and Asia.

Figure 1. Schematic overview of the data processing method adopted to generate the WorldPop gridded subnational dependency ratio datasets and high resolution gridded 5-year age/sex group count datasets.

Figure 2. Subnational young age dependency ratio (YDR) datasets, circa 2010.

(a) Shows dataset for Asia and (b) shows dataset for Africa. Note differing colour scales used between the two maps to highlight variations.

Figure 3. Circa 2010 High-resolution gridded population distribution presenting age structures for mainland Africa and Madagascar and the Asian region.

Estimates of young age population (0 to 14yrs) are in (a,c); estimates of working age population (15 to 65) are in (b,d). The grid cell resolution is 30 arc seconds (approximately 1 km at the equator) and coordinate reference system is GCS WGS 1984.

Figure 4. Differences between national and subnational young-age dependency ratios (YDR) for Asian and African countries.

(a) shows Asian countries and (b) shows African countries. For each country, the year of World Bank national estimates (red dots) correspond to the year of our data. The solid bold center line of the boxplot shows the median values, the box width represents the interquartile range, and the whiskers extend to 1.5 times the interquartile range from the box (values further away than this are shown as open circles). The administrative unit level of the sub-national data used here is shown in brackets next to the country name on the x-axis.