The World Bank produced its first global poverty estimates for developing
countries for World Development Report 1990: Poverty (World
Bank 1990) using household survey data for 22 countries (Ravallion,
Datt, and van de Walle 1991). Since then there has been considerable
expansion in the number of countries that field household
income and expenditure surveys. The World Bank’s Development
Research Group maintains a database that is updated regularly as
new survey data become available (and thus may contain more recent
data or revisions that are not incorporated into the table) and conducts
a major reassessment of progress against poverty about every
three years. The next comprehensive reassessment is due later this
year, and revised and updated poverty data will be published in the
World Development Indicators online tables and database.