When classifying countries by income group, the sample has high coverage of low and upper middle income countries (more than 82 percent), partial coverage of low income countries (76 percent) and low coverage of high income countries. The two types of countries most underrepresented in the data – those in the Middle East and North Africa and high income countries – tend to have low poverty rates. Therefore, the sample overstates developing world poverty rates in the aggregate, though it is less clear how omitting these countries affects the comparison between child and adult poverty rates; this will be explored in future work. All subsequent tables and figures in this report are based on the GMD sample presented in Table 2.

The GMD sample is lined up to represent estimates of extreme poverty in 2013. Lining up the welfare aggregates in surveys to a common year makes them more comparable across countries, since the underlying surveys in both PovcalNet and the GMD were conducted in various years. Between 2009 and 2014, population generally increased and poverty generally fell; therefore failing to line up poverty estimates to a common year would give older surveys less weight overall, but greater weight when generating profiles of the global poor. Lining up the survey data to 2013 entails adjusting both the population and the poverty estimates. To adjust the population, we utilize population projections for each gender and age group provided by the United Nations Population Division (UNDESA), which are available by gender and five-year age cohort. As a result of the line-up, the sum of the survey weights for each gender and age group within each country match UNDESA’s reported population of that group in 2013.<sup>9</sup> The poverty estimates are constructed to equal those published by PovcalNet for each country. Full details of this ‘lining up’ procedure are given in Castañeda et al 2016.

# **Poverty rates among children and adults**

How do the prevalence and depth of extreme poverty differ by age in the sample of 89 countries? Table 3 gives the prevalence results, which are striking. More than half of the extreme poor are children (aged under 18), even though children only comprise a third of the sample population. Among the extremely poor, children outnumber prime-age adults (aged 18-59) by a factor of 1.14, and the number of elderly aged 60 or more by a factor of 8.6. The extreme poverty rate for children is 19.5 percent, compared to 9.2 percent for adults, 9.5 percent for prime-aged adults aged 18-59, and 7 percent for people aged 60 or more. The large number of poor children reflects both the large share of youth in the population (32 percent) as well as high rates of child poverty (19.5 percent).

Poverty rates among children rise slightly for young children, then decline as age group increases. Children aged 5 to 9 are most likely to be poor, at 21.5 percent, followed by children age 0 to 4 at 21 percent, 18.7 percent of 10 to 14 year olds, and 14.6 percent of the oldest group of children aged 15 to 17. Lower poverty rates among older children may stem from the lifetime earning cycle of their parents (older parents with more working experience tend to earn higher income), the labor force participation of spouses and older children, and fewer dependants, although further investigation would be required to determine their relative importance.

> 9 These population estimates are for five-year age groups; we distribute the population uniformly across years of age within these groups.

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