This paper uses a set of national household surveys to study the regional Sub-Saharan Africa distribution of consumption expenditure among individuals during 1993 to 2008. The analysis puts the disparities in living standards that exist among persons in Africa into context with the disparities that exist within and between African countries.

This paper ignores national boundaries and studies the Sub-Saharan-Africa-wide distribution of consumption expenditure among individuals. By combining household survey data from as many African countries as possible (accounting for around three-quarters of the regional population), we can put all Africans on the same scale of consumption expenditure, regardless of their country of residence. Inequality and other distributional characteristics are typically measured at the countrylevel (e.g. for a recent review of the evidence on Sub-Saharan Africa, see Beegle et al., 2016). This paper offers a complementary view and puts the disparities that exist within African countries into context with the disparities that exist within the region as a whole.

Our analysis is similar to studies of the global income distribution (Milanovic, 2005, Anand and Segal, 2015; Ravallion, 2014a) and we draw heavily on the analysis by Lakner and Milanovic (2015). Our analysis is perhaps best seen as referring to a sub-region of the global distribution. According to Milanovic (2005), there are three concepts of global inequality: (1) the inequality in per capita incomes between countries in the world, which is relevant to studies of income convergence across countries; (2) population-weighted international inequality, which assigns everyone the per capita income of their country of residence; and (3) interpersonal inequality, where everyone is assigned their own income. In this paper, we study the third concept as applied to Sub-Saharan Africa, i.e. the inequality in consumption expenditure among all people living in Sub-Saharan Africa. Implicit in our analysis is an African-wide social welfare function which treats persons irrespective of their country of residence. In the global context, this is referred to as a cosmopolitan social welfare function (Atkinson and Brandolini, 2010). One might also have an instrumental concern for regional interpersonal inequality if extreme regional inequality contributes to conflict or migration.

The analysis in this paper is based on a database of national household surveys from Sub-Saharan Africa maintained by the World Bank, over the period 1993 to 2008. Our welfare measure is consumption expenditure per capita as measured in household surveys, expressed in 2011 PPP USD, although the results are robust to using 2005 purchasing power parity (PPP) exchange rates. While our database of household surveys has a good coverage of Africa as a whole (representing three-quarters of the regional population), the coverage of fragile countries remains low. Hence our results are probably a lower bound on African inequality. Another reason for why our estimates are likely to be a lower bound is that we use consumption expenditure surveys which most likely underestimate consumption at the top of the distribution.

Between 1993 and 2008, interpersonal inequality for Sub-Saharan Africa as a whole increased. For example, the Africa-wide Gini increased from 52% in 1993 to 56% in 2008. By contrast, Beegle et al. (2016) find no systematic increase of within-country inequality in the region. Taken together, the country-decomposition of regional inequality shows that the rise in regional inequality was driven by increasing inequality between countries, i.e. an increasing dispersion in average consumption across countries. However, within-country differences continue to dominate the level of African inequality. The African growth incidence curve is upward-sloping, consistent with the increasing inequality. While mean African consumption grew at around 1% per year, living standards for the bottom third of the distribution stagnated, while the top 5% received some 40% of the total gains between 1993 and 2008 (with a growth rate of around 2% per year).

The paper is structured as follows. First, we explain the construction of our database, and then show summary statistics. Section IV presents results for the cross-sectional distribution and its inequality. Overall African inequality is decomposed into between- and within-country components in Section V. In Section VI, we study growth incidence curves, looking at both relative and absolute gains along the distribution. Section VII compares these results with what can be learnt from GDP per capita alone. We analyze relative movements over time of specific country groups in the regional distribution in Section VIII, and the final section concludes. The Appendix presents a number of robustness checks, especially the results with the 2005 PPPs. Throughout, we draw comparisons with regional results for East Asia and Pacific from a companion paper (Jirasavetakul and Lakner, forthcoming). In the early 1990s, average consumption per capita was comparable in the two regions or even slightly lower in East Asia. However, since then growth in East Asia has been much faster and, while regional inequality also increased, its growth appears less concentrated than in Africa.

This paper is a product of the Office of the Chief Economist, Africa Region and the Poverty and Equity Global Practice Group. It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world. Policy Research Working Papers are also posted on the Web at http://econ.worldbank.org.