For a long time, as a college professor and then as the chief economic adviser to the Indian government, I was a happy user of the World Bank’s data on global poverty, tracking trends and analyzing cross-country patterns. I seldom paused to think about how those numbers were computed. Then, three years ago, I joined the World Bank as its Chief Economist. It was like a customer, happily ordering dinner in a favorite restaurant, suddenly being asked to go into the kitchen and prepare the meal.
World Bank researchers have been trying to assess the extent of extreme poverty across the world since 1979 and more systematically since the World Development Report 1990, which introduced the dollar-a-day international poverty line. From the beginning, the idea was to measure income poverty with respect to a demanding line which, first, reflects the standards of absolute poverty in the world’s poorest countries and, second, corresponded to the same real level of well-being in all countries. The first requirement led researchers to anchor the international poverty line on the national poverty lines of very poor developing countries. And the second requirement led them to use purchasing power parity exchange rates (PPPs) – rather than nominal ones - to convert the line into the US dollar and, more importantly, into the currencies of each developing country.
Achieving shared prosperity, one of the World Bank’s twin-goals, isn’t just a middle-income country’s preoccupation. It has a special resonance in Tanzania, a US$1,000 per capita economy in East Africa.
Tanzania has seen remarkable economic growth and strong resilience to external shocks over the last decade. GDP grew at an annualized rate of approximately 7 percent. Yet, this achievement was overshadowed by the slow response of poverty to the growing economy. The poverty rate has remained stagnant at around 34 percent until 2007 and started a slow decline of about one percentage point per year, attaining 28.2 percent in 2012. To date, around 12 million Tanzanians continue to live in poverty, unable to meet their basic consumption needs, and more than 70 percent of the population still lives on less than US$2 per day. Promoting the participation of the poor in the growth process and improving their living standards remains a daunting challenge.
However, does economic growth affect poverty reduction equally in different countries? Contrary to conventional wisdom, we don’t think so. And here’s why.