Recent studies have sought to explain which factors affect the income-poverty and inequality-poverty elasticities. Ravallion and Chen (1997) used a sample of developing countries to demonstrate income-poverty elasticity (measured by the number of people with incomes below the poverty line of one dollar a day), finding this elasticity to be -3. This means that for every 1% rise in the average income, the proportion of individuals with incomes below the poverty line falls by 3%.