世界银行-价格调整与贫困衡量（英）-2023.4-51页_614kb

The paper "Price Adjustments and Poverty Measurement" by Amendola, Mancini, Redaelli, and Vecchi (2023) investigates the impact of price adjustment methods on poverty and inequality measurements. Here is the key analysis:

• Interpersonal welfare comparisons must account for price differences over time and across regions to accurately measure poverty.
• The main result suggests using a single price index (SI), such as the total Consumer Price Index (CPI), for deflating consumption aggregates is better than using multiple indexes (MI), like food-specific and non-food-specific deflators, as SI reduces bias in welfare rankings.
• SI adjustment minimizes systematic errors, while MI can lead to biases based on household food budget shares and relative price levels (e.g., if food prices rise faster than non-food, higher-spending households are penalized).
• The sequencing of price adjustments matters: temporal (intra-survey) inflation adjustments should precede spatial cost-of-living adjustments to ensure accurate unit values and budget shares.
• Empirical evidence from Iran's 2019 Household Expenditure Survey shows biases ranging from 5-10% in national poverty rates to over 30% at district levels with incorrect MI use, affecting poverty and inequality measures significantly.
• Practical guidelines: Adjust all expenditures for inflation first, then use a single index for spatial deflation, to maintain consistency in welfare comparisons.

This analysis underscores that while MI may seem precise, it can systematically distort poverty measures, favoring SI for accurate policy-relevant outcomes.