Migration and Household Surveys: Sampling Design

1. Migration and Household Surveys: Sampling Design Johan A. Mistiaen The World Bank DECDG Nairobi, kenya 11 December 2006

2. Sampling Design: 2 Approaches • Probability Sampling (PS) • Each member of the target population has a known, nonzero selection probability • Random sampling methods used • Non-Probability Sampling (NPS) • Based on subjective judgments • Require models to analyze and interpret • Probability Sampling is generally preferred but depends…

3. Considerations in Sampling Design • 2 Key Challenges with Constructing Probability Samples for the Study of Migration and Remittances: • Sampling frames for population sub-groups that migrate, send or receive remittances are generally non-existent so they must be constructed; and • These sub-groups are typically “Rare Elements” in the population and is often equivalent to finding a needle in a haystack.

4. Research Gaps: PS vs NPS Approaches • Basic Questions: • What is the appropriate sampling technique under different circumstances? • Migrants, Non-Migrants and Return Migrants • Remittance Senders vs. Recipients • Addressing endogeneity • What are the trade-offs in terms of: • Bias (sampling and non-response), • Study Costs • Implementation Time

5. Research Project: The Brazil Nikkei Household Survey • Objectives: • Ascertain key determinants, constraints, socio-economic and welfare impacts of international migration by Japanese-Brazilians to, settlement in and return from Japan to inform development policy; • Test 3 different sampling approaches for survey bias trade-offs

6. Research Project: The Brazil Nikkei Household Survey • Background Facts: • Brazil is home to about 1.3 million Japanese descendents - Nikkei (migration started in 1908, the 6th generation is now being born); • Today approximately 275,000 Nikkei from Brazil live and work in Japan; • Remittances back to Brazil are estimated to be approximately US$ 2.2 billion annually (Ministry of Foreign Affairs, Government of Japan), almost equal to annual export value from Brazil to Japan; Survey Design Implications ! • The 1990 revision of Japan's Immigration Law allows for legal migration up and to third-generation Nikkei; • Nikkei in Brazil are frequently targeted for robbery by criminal gangs.

7. Research Project: The Brazil Nikkei Household Survey Sampling Design Challenge • Needle-in-a-Haystack: • About 1.4 million Japanese-Brazilians (target population) in Brazil which is less than 1% of the total population (177 million) => COSTS • Geographically Clustered: • Vast majority of target population resides in neighborhoods located in the states of Sao Paulo (54%) and Parana (26%). Source: 2000 population census

8. Research: The Brazil Nikkei Household Survey • Test 3 Sampling Design Approaches: • Random Disproportionate Stratified Sampling (PS) • Snowball Sampling (NPS) • Aggregation Point Intercept Sampling (NPS)

9. Research: The Brazil Nikkei Household Survey • Random Disproportionate Stratified Sampling (PS) • Census-based target clusters identified

10. Nikkei Target clusters in the State of Sao Paulo

11. Research: The Brazil Nikkei Household Survey • Random Disproportionate Stratified Sample (PS) • Census-based target clusters identified • Listing conducted in the PPS selected clusters • Households randomly PPS sampled from lists • F2F interviews by Nikkei enumerators • Stratified by geography, migrant status and generational characteristics • Will yield benchmark PS

12. Research: The Brazil Nikkei Household Survey • Snowball Sample (NPS) • 25 Nikkei Diaspora associations contacted to request “seed” households • 70 seed households identified via 20 Nikkei Diaspora associations • Exhaustive surveying of the referral-chain network identified via the seed households to minimize bias (Heckathorn, 1997, 2002)

13. Research: The Brazil Nikkei Household Survey • Aggregation Point Intercept Sample (NPS) • 11 fixed locations and 6 events identified in Sao Paulo • F2F interview using short 10 min questionnaire • Interview for fixed time period (e.g., 2 hours) • 2 interviewers: one conducts interview, other records number of potential respondents passing the location

14. Research Project: The Brazil Nikkei Household Survey • Some Key Research Questions: • Compare data (identical questions) from the PS random sample with the population census and nationally representative household survey (often used to study migration/remittances) • Compare data from the 2 NPS with PS • Assess impact of migration/remittances by matching households across the legislation-induced generational control

15. Research Project: The Brazil Nikkei Household Survey • Key Emerging Challenge: • Non-Response: Attempt to minimize via (a) using Nikkei interviewers, (b) Nikkei Diaspora endorsement and (c) after F2F refusal, leave copy of questionnaire that can be mailed • Completion of data collection in January 2007 • Draft research paper will be circulated in February 2007