2011年-世界发展银行全球_Migration_and_Economic_Mobility_in_Tanzania___Evidence_from_a_Tracking_Survey_24页_462kb

Summary of "Migration and Economic Mobility in Tanzania: Evidence from a Tracking Survey"

Core Content

This study investigates the impact of migration on economic mobility and poverty reduction in Tanzania, specifically in the Kagera region, using a thirteen-year panel survey. The analysis focuses on how physical movement from one's original community affects consumption growth and poverty levels.

Main Findings

• Migration and Consumption Growth: Migration between 1991 and 2004 contributed significantly to consumption growth, adding 36 percentage points to consumption growth. The average consumption change for migrants was more than four times greater than for non-migrants.
• Regional Migration Effects:
  • Individuals who remained in their original community saw a 3 percentage point decrease in poverty.
  • Those who moved to neighboring communities experienced a 12 percentage point reduction in poverty.
  • Migrants who moved outside Kagera saw a 23 percentage point decline in poverty.
• Poverty Reduction in Kagera: Overall, poverty in Kagera decreased by 8 percentage points, but this was largely due to migration. Without tracking migration, poverty reduction would have been underestimated by about half.
• Sectoral Mobility: Moving out of agriculture led to higher growth than staying in it, but growth was always greater for individuals who physically moved, regardless of the sector.
• Key Methodology: The study uses panel data and within-household variation to control for unobserved heterogeneity. It compares siblings and other relatives who moved or stayed, allowing for a more accurate estimation of migration's impact.

Key Insights

• Migration as a Strategy: Migration is part of a broader welfare-maximizing livelihood strategy, involving risk sharing and income growth.
• Unobserved Heterogeneity: The study acknowledges that unobserved factors may influence migration decisions and consumption outcomes. However, the use of fixed-effects models and 2SLS helps to mitigate this issue.
• Non-Random Migration: The assumption that migration is random within households is challenged, as the Harris-Todaro model suggests that earnings differentials drive migration, implying that those who move may have greater earning potential.
• Exit Barriers: The study concludes that exit barriers set by home communities—such as social and family norms—prevent some individuals from migrating, even when the benefits are high. There is no evidence of financial constraints to migration.

Data Overview

• KHDS Panel Survey: Conducted by the World Bank and Muhimbili University College of Health Sciences, the survey tracked 915 households over 1991–1994 and reinterviewed individuals in 2004.
• Reinterview Rates: 93% of baseline households were reinterviewed, which is higher than most panel surveys in low- and high-income countries.
• Consumption Data:
  • Consumption is measured in annual per capita terms.
  • The poverty line is set at TSh 109,663, calibrated to match the 2000/01 National Household Budget Survey estimate for Kagera.
  • The U.S. dollar was valued at around TSh 1,100 during the survey period.

Economic Mobility and Migration

• Mobility and Wealth: Migration significantly increases consumption and wealth, with those who moved outside Kagera seeing the largest increase (up to TSh 291,767).
• Poverty Dynamics: The poverty head count decreased more sharply for those who migrated than for those who stayed.
• Robustness Checks: The results are robust across different measures of consumption and poverty, indicating a consistent positive impact of migration.

Conclusion

The study provides strong evidence that migration improves economic outcomes and reduces poverty in Tanzania. Despite the high returns of migration, exit barriers from home communities—primarily social and family norms—prevent many from migrating. The tracking survey methodology used in this study is crucial for capturing the true impact of migration on economic mobility and poverty reduction.