马达加斯加2012-2021年全国贫困率趋势估算

Estimating a trend in the nationalpoverty rate 2012-2021 in Madagascar Nobuo Yoshida,Francis Mulangu,Ana Maria Oviedo,Haoyu Wu,Tomoyuki Sho,Danielle AronandOlive UmuhireNsababeraPublic Disclosure Authorized September2025 Keywords:Poverty measurement;International poverty line;Inflation andprice indices;Survey-to-survey (S2S) imputation. Public Disclosure Authorized Development Data GroupDevelopment Research Group Abstract The standard global poverty estimation method—relying on household survey data andCPI-based inflation—suggests a sharp decline in Madagascar’s international poverty rate(measured at $3 per day in PPP terms) between 2012 and 2021. This paper, however,applies a survey-to-survey imputation method—SWIFT (Survey of Wellbeing via Instantand Frequent Tracking)—to show that official CPI estimates significantly understateactual inflation. Once corrected, the data reveals poverty stagnation rather than decline,aligning more closely with other socio-economic indicators. The analysis also extends All authors were with the World Bank at the time of writing.Corresponding author:Nobuo Yoshida(nyoshida@worldbank.org).We would like to acknowledgeDaniel Gerszon Mahler,Christoph Lakner,Gabriel Lara Ibarra, andMinh Cong Nguyenfor their advice, comments, and suggestions. Also, wewould like to thank all participants in multiple sessions ofthetechnicalGlobalPovertyWorkingGroupat the World Bank for their comments. Lastly, we would like to thankRinku Murgai,Gabriela Inchauste, 1.Introduction Two major challenges compromise the accuracy of estimating the national poverty trend inMadagascar between 2012 and 2021/22. Typically, such analyses presume that consumption datafrom successive surveys are comparable and that inflation rates, based on Consumer Price Indexes(CPIs), are accurately calculated. However, these assumptions may not hold true for Madagascar.Firstly, the comparability of consumption data across the last two survey rounds is questionable.The Enquête Périodique auprès des Ménages (EPM) 2021-22, adhering to LSMS guidelines,featured an extensive consumption module. In contrast, prior to 2021, the national statistics office The standard poverty trend analysis for Madagascar from 2012 to 2021 indicates a significantreduction in poverty levels, potentially influenced by changes in survey modules and anunderestimation of inflation through CPI calculations. When the consumptiondata from EnquêteNationale sur leSuivi des OMD (ENSOMD) 2012 and EPM 2021/22 are examined with the 2021National Poverty Line (NPL), adjusted for CPI, the poverty rate, measured at the national poverty To address the survey design change and possible underestimation of the CPI-based inflation, asurvey-to-survey (S2S) imputation technique called the SWIFT (Survey of Wellbeing via Instantand Frequent Tracking) approach is taken. The S2S methodology trains a model for imputinghousehold expenditure in a survey and applies it to impute household expenditures in anothersurveywhere its household expenditures are not comparable to the other survey’s.ForMadagascar, SWIFT trains urban, capital city, and rural imputation models in EPM 2021/22 data A similar comparability problem arises when estimating poverty using the International PovertyLine (IPL) if actual consumption data of the 2012 and 2021 are used. A standard procedure tocalculate IPL is to convert the poverty line of $3 a day to local currency using the 2021 PPPconversion factor and inflate (or deflate) it using the inflation rate between the survey year and There are two possible explanations for thisapparent discrepancy: 1) the CPI, which is used in thestandard international poverty measures, underestimates inflation, and 2) the new EPM 2021/22 Box 1. Reliability of the SWIFT approach 2.Issues of CPI-based inflation rates The Consumer Price Index (CPI) in Madagascar, estimated by Institut National de la Statistique(INSTAT), is a critical economic indicator used to measure changes in the price levels of a basket First, outdated consumption weights in the CPI fail to reflect significant shifts in consumerbehavior. The CPI is calculated using a basket of goods and services based on householdconsumption patterns, but the weightings for these items were last updatedin 2012 using the Secondly, the data sources for price collection have not been updated in 20 years. Many points ofsale in the sample have ceased operations but were not replaced, further eroding the sample’srepresentativeness. Collection biases also persist, as price data is manually recorded or gatheredthrough phone calls, often without verifying actual transaction prices. This introduces significant These challenges became significantly more pronounced after 2020 when the data collectionprocess shifted to phone-based surveys due to resource constraints. This shift resulted in limitedcoverage and verification, further weakening its reliability. Although INSTAT attempted tomodernize the CPI in 2020 by shifting