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Respondent Driven Sampling (RDS)

Respondent Driven Sampling (RDS). Keith Chan BC CfE. RDS of drug users in Recife, Brazil. IDU. DU. www.respondentdrivensampling.org Douglas Heckathorn, Cornell. Obstacles. Hard to reach populations Lack of sampling frame Convenience sample Biased estimates Not generalizable. RDS hopes.

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Respondent Driven Sampling (RDS)

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  1. Respondent Driven Sampling (RDS) Keith Chan BC CfE

  2. RDS of drug users in Recife, Brazil IDU DU

  3. www.respondentdrivensampling.orgDouglas Heckathorn, Cornell

  4. Obstacles Hard to reach populations Lack of sampling frame Convenience sample Biased estimates Not generalizable

  5. RDS hopes • Valid identification of population members • Population-based estimates • Efficient recruitment of hidden populations

  6. RDS issues Many assumptions and requirements Many potential biases may not disappear Difficulties in analysis of RDS data Success and failures of RDS worldwide

  7. RDS Assumptions • Recruits who’s network is members of the target population • Network forms one single large component • Report network size accurately • Recruit randomly from network • Sampling with replacement

  8. RDS Necessary Data Requirements • Personal Network Size • Respondent's Serial Number - Serial number of the coupon the respondent was recruited with • Respondent's Recruiting Serial Numbers - Serial numbers from the coupons the respondent is given to recruit others

  9. Important Coupon Information

  10. RDS of drug users in Recife, Brazil IDU Non IDU

  11. RDS study of MSM, Kampala, Uganda

  12. Markov Process Assumption • Memoryless • As the recruitment process continues from wave to wave, an equilibrium mix of recruits will eventually be attained • This equilibrium mix is independent of the characteristics of the subject from which the recruitment began

  13. Equilibrium of education, MSM, Uganda Completed high school Did not complete high school

  14. Equilibrium of sex with foreigners, MSM, Uganda No foreign sex partner Had any foreign sex partner

  15. Network Size Question Meant to assess the size of the network from which a person could actually recruit within a reasonable time How many other ____ do you know and you will see in the next month? How many other ____ do you know and you will see in the next week?

  16. Reciprocal Relationship Assumption

  17. Analysis Sample size calculation Crude vs. adjusted Univariate Bivariate Weights Multivariate Netdraw Aggregate analyses Statistical tests Design effect adjustment

  18. RDS of drug users in Recife, Brazil IDU seed Never grew. Requested from Brazilia permission to change to all drug users.

  19. RDS of drug users in Recife, Brazil IDU DU

  20. Kosovo Russia IDU: Failures

  21. Mexico Vietnam USA Estonia Nepal Iran Russia Thailand Montenegro Serbia India Indonesia IDU: Successes

  22. Caribbean Paraguay Serbia, Montenegro, Albania, Russia Female sex workers: Failures

  23. Honduras Vietnam India Papua New Guinea Female sex workers: Successes

  24. Estonia Caribbean Cambodia Albania Kosovo MSM: Failures

  25. USA Honduras Egypt Croatia Nepal Iran Brazil Uganda Thailand Zanzibar Papua New Guinea Bangladesh South Africa MSM: Successes

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