| Is the incidence and
depth of poverty rising in the world? Does income inequality
increase with rising average standards of living? How much do the
poor share in the benefits of higher average levels of living? How
much do they lose from aggregate contraction? These questions are
often asked. But they are hard questions to answer
convincingly.
In principle, household surveys can
address such questions. But coverage and quality are uneven. Data on
poor people has historically been wanting relative to most other
data. For example, the 1979 World Development Report (WDR),
and the WDRs for many years after, only gave distributional data
from household surveys for 20 or so developing countries. Yet
macroeconomic aggregates were available for almost all
countries.
The availability of distributional data
for developing countries has improved over the last 10 years. For
example, the 2000 issue of World Development Indicators gives
distributional data for 90 low and middle income countries. The
timeliness of data has also improved. In the 1985 WDR, the average
lag was 11 years (so the average survey date was 1974!). The lag is
now under five years. Efforts at improving data quality and country
coverage have been made by many countries and international
agencies, including the World Bank. There is a long way to go before
we can even say that the all poor countries have a good quality
survey for poverty monitoring, and even further before we can be
confident of data comparability across countries and over time. But
there has been progress.
Drawing on the set of suitable household
surveys currently available, this web site provides access to
estimates of various poverty and inequality measures made by staff
of the World Bank’s Research Group with considerable help from their
colleagues in the bank’s regional units. Unlike past compilations of
distributional data across countries, all these estimates have been
based on the primary survey data (either in raw form or
specially-designed tabulations from the raw data). No pre-existing
estimates from other compilations or country studies have been used.
This allows some obvious comparability problems to be avoided. But
there are problems that cannot be avoided, such as stemming from
differences between countries or over time in the survey design.
When a serious problem is known to exist, a survey might be dropped.
But many problems remain. Continuing efforts are being made to
improve the estimates.
The methods used are summarized in the
paper, "How did the world’s poorest fare in the 1990s?" that can be
downloaded from this site. References are also given to various
papers by those involved in the project, using household surveys to
measure poverty and inequality, and to assess anti-poverty
policies. | 
