Deflation by Expenditure Components: A Harmless Adjustment?
研究了生活成本调整的微小特征如何影响家庭支出分布，发现使用单一价格指数调整消费总量比分别调整子成分更优，后者会导致福利度量系统偏差，进而影响贫困和不平等测量。
Abstract We investigate the effect that seemingly minor features of the implementation of cost‐of‐living adjustments have on the distribution of household expenditures, by developing an analytical framework that is consistent with standard consumer theory, and mindful of data limitations faced by practitioners. The main result is at odds with common sense: even when multiple price indices are available (e.g., a food Consumer Price Index and a non‐food one), it turns out that using a single price index (e.g., the total Consumer Price Index), to adjust the consumption aggregate is recommended. The practice of adjusting subcomponents of consumption separately (food with a food index and nonfood with a nonfood index) can lead to a systematic bias in the welfare measure, and consequently in poverty and inequality measures. Using Iran's 2019 Household Expenditures and Income Survey, we find that the bias manifests as a systematic underestimation of urban poverty and overestimation of rural poverty.