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Abstract
Spatially disaggregated maps of the incidence of poverty can be constructed by
combining household survey data and census data. In some cases, however, statistical
authorities are reluctant, for reasons of confidentiality, to release household-level census
data. This paper examines the loss in precision associated with using aggregated census
data, such as village- or district-level means of the data. We show analytically that using
aggregated census data will result in poverty rates that are biased downward (upward) if
the rate is below (above) 50 percent and that the bias approaches zero as the poverty rate
approaches zero, 50 percent, and 100 percent. Using data from Vietnam, we find that the
average absolute error in estimating provincial poverty rates is about 2 percentage points
if the data are aggregated to the enumeration-area level and around 3-4 percentage points
if they are aggregated to the provincial level. Even census data aggregated to the
provincial level perform reasonably well in ranking the 61 provinces by the incidence of
poverty: the average absolute error in ranking is 0.92.