Migration and Migration and Household Surveys: Household Surveys: Sampling DesignSampling Design

Johan A. MistiaenJohan A. MistiaenThe World BankThe World Bank

DECDGDECDGNairobi, kenyaNairobi, kenya

11 December 200611 December 2006

Sampling Design: 2 Sampling Design: 2 ApproachesApproaches1.1. Probability Sampling (PS)Probability Sampling (PS)

– Each member of the target population Each member of the target population has a known, nonzero selection has a known, nonzero selection probabilityprobability

– Random sampling methods used Random sampling methods used

2.2. Non-Probability Sampling (NPS)Non-Probability Sampling (NPS)– Based on subjective judgmentsBased on subjective judgments– Require models to analyze and interpretRequire models to analyze and interpret

Probability Sampling is generally Probability Sampling is generally preferred but depends…preferred but depends…

Considerations in Sampling Considerations in Sampling DesignDesign 2 Key Challenges with Constructing 2 Key Challenges with Constructing

Probability Samples for the Study of Probability Samples for the Study of Migration and Remittances: Migration and Remittances:

1.1. Sampling frames for population sub-groups Sampling frames for population sub-groups that migrate, send or receive remittances that migrate, send or receive remittances are generally non-existent so they must be are generally non-existent so they must be constructed; andconstructed; and

2.2. These sub-groups are typically “Rare These sub-groups are typically “Rare Elements” in the population and is often Elements” in the population and is often equivalent to finding a needle in a equivalent to finding a needle in a haystack.haystack.

Research Gaps: Research Gaps: PS vs NPS ApproachesPS vs NPS Approaches Basic Questions: Basic Questions:

– What is the appropriate sampling What is the appropriate sampling technique under different technique under different circumstances?circumstances?

Migrants, Non-Migrants and Return MigrantsMigrants, Non-Migrants and Return Migrants Remittance Senders vs. RecipientsRemittance Senders vs. Recipients Addressing endogeneityAddressing endogeneity

– What are the trade-offs in terms of: What are the trade-offs in terms of: Bias (sampling and non-response),Bias (sampling and non-response), Study CostsStudy Costs Implementation Time Implementation Time

Research Project: Research Project: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey Objectives:Objectives:

– Ascertain key determinants, Ascertain key determinants, constraints, socio-economic and constraints, socio-economic and welfare impacts of international welfare impacts of international migration by Japanese-Brazilians to, migration by Japanese-Brazilians to, settlement in and return from Japan to settlement in and return from Japan to inform development policy;inform development policy;

– Test 3 different sampling approaches Test 3 different sampling approaches for survey bias trade-offsfor survey bias trade-offs

Research Project: Research Project: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey Background Facts:Background Facts:

1.1. Brazil is home to about 1.3 million Japanese Brazil is home to about 1.3 million Japanese descendents - Nikkei (migration started in 1908, the descendents - Nikkei (migration started in 1908, the 6th generation is now being born);6th generation is now being born);

2.2. Today approximately 275,000 Nikkei from Brazil live Today approximately 275,000 Nikkei from Brazil live and work in Japan;and work in Japan;

3.3. Remittances back to Brazil are estimated to be Remittances back to Brazil are estimated to be approximately US$ 2.2 billion annually (Ministry of approximately US$ 2.2 billion annually (Ministry of Foreign Affairs, Government of Japan), almost equal Foreign Affairs, Government of Japan), almost equal to annual export value from Brazil to Japan;to annual export value from Brazil to Japan; Survey Design Implications !Survey Design Implications !

4.4. The 1990 revision of Japan's Immigration Law allows The 1990 revision of Japan's Immigration Law allows for legal migration up and to third-generation Nikkei;for legal migration up and to third-generation Nikkei;

5.5. Nikkei in Brazil are frequently targeted for robbery by Nikkei in Brazil are frequently targeted for robbery by criminal gangs.criminal gangs.

Sampling Design ChallengeSampling Design Challenge Needle-in-a-Haystack:Needle-in-a-Haystack:

– About 1.4 million Japanese-Brazilians About 1.4 million Japanese-Brazilians (target population) in Brazil which is (target population) in Brazil which is less than 1% of the total population less than 1% of the total population (177 million) => (177 million) => COSTSCOSTS

Geographically Clustered:Geographically Clustered:– Vast majority of target population Vast majority of target population

resides in neighborhoods located in resides in neighborhoods located in the states of Sao Paulo (54%) and the states of Sao Paulo (54%) and Parana (26%). Parana (26%). Source: 2000 population Source: 2000 population censuscensus

Research Project: Research Project: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey

Research: Research: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey Test 3 Sampling Design Test 3 Sampling Design

Approaches:Approaches:

1.1. Random Disproportionate Stratified Random Disproportionate Stratified Sampling (PS)Sampling (PS)

2.2. Snowball Sampling (NPS)Snowball Sampling (NPS)

3.3. Aggregation Point Intercept Aggregation Point Intercept Sampling (NPS)Sampling (NPS)

Research: Research: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey1.1. Random Disproportionate Stratified Random Disproportionate Stratified

Sampling (PS)Sampling (PS) Census-based target clusters identifiedCensus-based target clusters identified

Nikkei Target clusters in the State of Sao Paulo

Research: Research: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey1.1. Random Disproportionate Stratified Random Disproportionate Stratified

Sample (PS)Sample (PS) Census-based target clusters identifiedCensus-based target clusters identified Listing conducted in the PPS selected Listing conducted in the PPS selected

clustersclusters Households randomly PPS sampled from Households randomly PPS sampled from

listslists F2F interviews by Nikkei enumeratorsF2F interviews by Nikkei enumerators Stratified by geography, migrant status Stratified by geography, migrant status

and generational characteristics and generational characteristics Will yield benchmark PSWill yield benchmark PS

Research: Research: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey2.2. Snowball Sample (NPS)Snowball Sample (NPS)

25 Nikkei Diaspora associations contacted 25 Nikkei Diaspora associations contacted to request “seed” householdsto request “seed” households

70 seed households identified via 20 70 seed households identified via 20 Nikkei Diaspora associationsNikkei Diaspora associations

Exhaustive surveying of the referral-chain Exhaustive surveying of the referral-chain network identified via the seed network identified via the seed households to minimize bias (Heckathorn, households to minimize bias (Heckathorn, 1997, 2002)1997, 2002)

Research: Research: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey3.3. Aggregation Point Intercept Sample Aggregation Point Intercept Sample

(NPS)(NPS) 11 fixed locations and 6 events identified 11 fixed locations and 6 events identified

in Sao Pauloin Sao Paulo F2F interview using short 10 min F2F interview using short 10 min

questionnairequestionnaire Interview for fixed time period (e.g., 2 Interview for fixed time period (e.g., 2

hours)hours) 2 interviewers: one conducts interview, 2 interviewers: one conducts interview,

other records number of potential other records number of potential respondents passing the locationrespondents passing the location

Research Project: Research Project: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey Some Key Research Questions:Some Key Research Questions:

1.1. Compare data (identical questions) from Compare data (identical questions) from the PS random sample with the the PS random sample with the population census and nationally population census and nationally representative household survey (often representative household survey (often used to study migration/remittances)used to study migration/remittances)

2.2. Compare data from the 2 NPS with PSCompare data from the 2 NPS with PS

3.3. Assess impact of migration/remittances Assess impact of migration/remittances by matching households across the by matching households across the legislation-induced generational control legislation-induced generational control

Research Project: Research Project: The Brazil Nikkei Household The Brazil Nikkei Household SurveySurvey Key Emerging Challenge:Key Emerging Challenge:

1.1. Non-Response: Attempt to minimize Non-Response: Attempt to minimize via (a) using Nikkei interviewers, (b) via (a) using Nikkei interviewers, (b) Nikkei Diaspora endorsement and (c) Nikkei Diaspora endorsement and (c) after F2F refusal, leave copy of after F2F refusal, leave copy of questionnaire that can be mailedquestionnaire that can be mailed

Completion of data collection in Completion of data collection in January 2007January 2007

Draft research paper will be Draft research paper will be circulated in February 2007 circulated in February 2007