Can Poverty Levels Be Estimated Using Satellite Data?

Chris ElvidgeNOAA – National Geophysical Data Center

325 Broadway, E/GC2Boulder, Colorado 80305, U.S.AEmail: chris.elvidge@noaa.gov

K.E. Baugh, B.T. Tuttle, A.T. Howard and P.J. Hayes

University of Colorado – CIRES325 Broadway E/GC2

Boulder, Colorado 80305, U.S.A

E.H. ErwinNOAA – National Geophysical Data Center

325 Broadway, E/GC2Boulder, Colorado 80305, U.S.A

July 17, 2006

Global PovertyGlobal Poverty The World Bank estimates that 40% The World Bank estimates that 40%

of all people live in poverty (2.6 of all people live in poverty (2.6 billion).billion).

The primary source for poverty The primary source for poverty estimates are household surveys and estimates are household surveys and government statistics (from tax government statistics (from tax reports, etc.).reports, etc.).

Poverty levels are reported for entire Poverty levels are reported for entire countries or states.countries or states.

Problems in Estimating Poverty Problems in Estimating Poverty LevelsLevels

It is difficult to define a uniform definition or It is difficult to define a uniform definition or method for measuring poverty.method for measuring poverty.

National definitions of poverty tend to be National definitions of poverty tend to be subjective. For instance many people counted as subjective. For instance many people counted as in poverty in the USA own automobiles – a sign of in poverty in the USA own automobiles – a sign of wealth in many other countries.wealth in many other countries.

Difficult to reconcile income versus consumption Difficult to reconcile income versus consumption based data from surveys.based data from surveys.

Not all countries measure or report poverty levels Not all countries measure or report poverty levels and the methods and timetables used vary and the methods and timetables used vary substantially.substantially.

It is possible for governments to bias poverty It is possible for governments to bias poverty estimates.estimates.

World Bank’s World Development World Bank’s World Development Indicator’s Poverty Map - 2005Indicator’s Poverty Map - 2005

Temporal Distribution of the Temporal Distribution of the National Poverty Data for 2005National Poverty Data for 2005

Estimation of Poverty Using Estimation of Poverty Using Satellite DataSatellite Data

Global coverage – making estimates Global coverage – making estimates where no other data are available.where no other data are available.

Standardized measurement.Standardized measurement. Uniform timing.Uniform timing. Disaggregated grid of poverty levels Disaggregated grid of poverty levels

has more applications than national has more applications than national level estimates for understanding level estimates for understanding poverty and planning solutions.poverty and planning solutions.

DOE LandScan 2004 Population DOE LandScan 2004 Population DensityDensity

Sources: Census data, MODIS land cover, SRTM topographyand high resolution satellite imagery.

DMSP Nighttime Lights - 2003DMSP Nighttime Lights - 2003

LandScan / LightsLandScan / Lights

CalibrationCalibration

Population Count in Poverty Population Count in Poverty Green 1-10, Yellow 11-50, Red > 50Green 1-10, Yellow 11-50, Red > 50

National Poverty EstimatesNational Poverty Estimates

Sub-national Poverty EstimatesSub-national Poverty Estimates

Poverty Poverty Estimates in Estimates in South and South and East AsiaEast Asia

(in percent)(in percent)

East TimorEast Timor 85.1185.11 BhutanBhutan 77.777.7 84.3184.31 PNGPNG 81.4581.45 LaosLaos 73.273.2 79.5079.50 MyanmarMyanmar 78.478.4 76.2676.26 NepalNepal 80.980.9 73.0373.03 DPRKDPRK 64.9464.94 MongoliaMongolia 74.974.9 56.5256.52 BangladeshBangladesh 82.882.8 52.9452.94 ChinaChina 46.746.7 44.6044.60 IndiaIndia 80.680.6 41.9441.94 PhilippinesPhilippines 47.547.5 41.1341.13 ThailandThailand 32.532.5 40.3940.39 VietnamVietnam 33.433.4 28.2828.28 IndonesiaIndonesia 52.452.4 33.3833.38 Sri LankaSri Lanka 50.750.7 30.2430.24 MalaysiaMalaysia 9.3 9.3 18.2318.23 JapanJapan 7.03 7.03 ROKROK 2.0 2.0 6.54 6.54 ROCROC 6.33 6.33 SingaporeSingapore 5.47 5.47

$2/day Satellite

Issues FoundIssues Found High poverty rates assumed for population High poverty rates assumed for population

with no detected lights – which may with no detected lights – which may overestimate poverty in wealthier overestimate poverty in wealthier countries.countries.

The nighttime lights product used has The nighttime lights product used has saturation in urban centers – introducing saturation in urban centers – introducing inaccuracies in poverty estimates in urban inaccuracies in poverty estimates in urban cores.cores.

There are cultural and technological There are cultural and technological differences in lighting that have not been differences in lighting that have not been accounted for. accounted for.

ConclusionsConclusions The first consistent global map of poverty levels The first consistent global map of poverty levels

has been produced.has been produced. Poverty levels have been estimated in a large Poverty levels have been estimated in a large

number of countries where data were not number of countries where data were not available previously.available previously.

Discrepancies between reported poverty levels Discrepancies between reported poverty levels and the satellite estimates probably arise both and the satellite estimates probably arise both from inaccuracies in the reported data and the from inaccuracies in the reported data and the satellite data / methodology / assumptions.satellite data / methodology / assumptions.

A new class of poverty map has been produced A new class of poverty map has been produced and can be expectd to impove in accuracy over and can be expectd to impove in accuracy over time. time.