Poverty reduction consistently ranks among the most prioritized tasks of developing countries as well as the international community. Indeed, the Sustainable Development Goals (SDGs) recently adopted by the United Nations General Assembly call for eliminating poverty by 2030 in its very first goal. A good understanding about poverty trends and dynamics could result in more efficient policies and better use of resources. For example, social protection programs may be most suitable to prevent vulnerable households from falling into poverty, but are not the best options to fight a situation of entrenched chronic poverty.
Several questions typically come up in the context of poverty measurement. One set of questions concerns, unsurprisingly, how best to track the trends of poverty over time? Put differently, how do we know which trajectory country A’s poverty is on: is it upward, downward, or does it remain flat over time? The other set of questions are related to the composition of poverty transitions over time. In particular, what is the proportion of the poor in one period that remain poor (i.e., chronic poverty) or escape poverty (i.e., upward mobility) in the next period? Or what is the proportion of the non-poor that fall into poverty (i.e., downward mobility) in the next period?
Yet, finding the answers to these questions are challenging tasks, simply because comparable household consumption data for a specific country from multiple time periods are often unavailable, particularly for low-income countries. As an example, using the World Bank’s database, we plot in Figure 1 the number of data points of poverty estimates for a country against its consumption level. For better presentation, we also graph the fitted line for the regression of the former outcome on the latter outcome.
The estimated slope of this regression line is positive and strongly statistically significant, suggesting that a 10 percent increase in a country’s household consumption is associated with almost one-third (i.e., 0.3) more surveys. Figure 1 thus helps highlight the—perhaps paradoxical—fact that poorer countries with a stronger need for poverty reduction also face a more demanding challenge of poverty measurement given their smaller numbers of surveys. This is unsurprisingly consistent with a prevailing among some development practitioners that collecting survey data may not be the top priority for many developing countries.