2007年-世界发展银行全球_Poverty_Analysis_Using_an_International_Cross-Country_Demand_System_56页_1mb

Summary of "Poverty Analysis Using an International Cross-Country Demand System"

Core Content

This paper introduces a novel method for ex ante poverty impact analysis resulting from policy reforms. The approach integrates micro-level household survey data with macro-level International Comparisons Project (ICP) data to estimate a global demand system, which is then calibrated to reflect country-specific behaviors. The authors use this calibrated demand system to evaluate the effects of a 5 percent increase in food prices on poverty levels in Indonesia, the Philippines, and Thailand, demonstrating how such price changes affect different income groups.

Main Innovations

1. Global Demand System Estimation:
   The paper proposes the use of a global demand system (AIDADS) that combines micro-data from household surveys and macro-data from the ICP. This system allows for more accurate representation of consumer behavior by aggregating individual household demands into national-level per capita demands.

2. Post-Estimation Calibration:
   A calibration method is introduced to adjust the global demand system to country-specific conditions, ensuring that the calibrated system reproduces observed per capita budget shares exactly. This calibration is critical for accurate welfare and poverty analysis.

3. Modified Foster-Greer-Thorbecke (FGT) Poverty Measure:
   The authors define a modified FGT poverty measure that uses a unique poverty level of utility, rather than income or expenditure-based measures. This allows for a more precise assessment of how changes in prices and consumption patterns affect poverty.

Key Findings

• The calibrated demand systems are able to reproduce observed per capita budget shares, making them suitable for predicting how changes in prices will affect consumption across different income levels.
• The 5 percent food price increase leads to a significant increase in poverty incidence and intensity in all three countries, though the specific effects vary.
• Subsistence Expenditures: At the lowest income levels, a large portion of additional expenditure is allocated to food and other non-durables, indicating the critical role of subsistence needs.
• Discretionary Expenditures: At higher income levels, the marginal budget share for services increases, showing the importance of discretionary spending in wealthier households.
• The paper highlights the limitations of traditional methods in predicting aggregate impacts, especially when using household survey data for cross-country comparisons.

Methodology

• The AIDADS model is an implicit, directly additive demand system that allows for non-linear Engel curves while maintaining a parsimonious parameterization.
• The model is estimated using a combination of ICP data and household survey data, with the focus on food, other non-durables, and services.
• A technical appendix provides details on the entropy-based estimation method, which minimizes a concentrated log-likelihood function and entropy function to estimate the demand system.
• The calibration process involves adjusting the estimated parameters to match observed per capita expenditure levels, ensuring that the model accurately reflects real-world behavior.

Data Sources

• ICP Data: Used for estimating the global demand system. It provides data on final consumption of 26 goods and services across 114 countries.
• Household Survey Data: Used to derive quintiles and deciles for expenditure distribution. The data are from Indonesia (1993), Thailand (1996), and the Philippines (1999).
• The calibrated demand system is applied to the three focus countries to assess the welfare and poverty impacts of a 5 percent food price increase.

Implications for Policy Analysis

• The approach allows for a more accurate and theoretically grounded analysis of how trade policy changes affect poverty.
• It is particularly useful for evaluating the distributional consequences of international price changes, as it accounts for both subsistence and discretionary spending.
• The calibrated model can be extended to other countries in the ICP dataset, enabling broader application in trade policy analysis.

Conclusion

The paper presents a comprehensive framework for analyzing poverty impacts of international trade reforms using a calibrated, internationally comparable demand system. It emphasizes the importance of considering both subsistence and discretionary expenditures in poverty analysis and provides a robust method for evaluating the welfare effects of policy shocks. This approach offers a valuable tool for policymakers and researchers seeking to understand the potential impacts of trade reforms on poverty levels.