Lisa g. Johnston , [email protected]
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Transcript of Lisa g. Johnston , [email protected]
Sampling Adolescents/Young Key Populations (A/YKP) at Risk of HIV Exposure Using Respondent Driven Sampling (RDS)L ISA G . JOHNSTONWWW.L ISAGJOHNSTON.COM, LS JOHNSTON.GLOBAL@GMAIL .COMUNIVERSITY OF CAL IFORNIA , SAN FRANCISCOTUL ANE UN IVERS ITY, NEW ORLEANS
OutlineoWhy is RDS superior for sampling A/YKP?oRDS OverviewoRDS Challenges oRDS Resources
Why is RDS superior for sampling A/YKP?
◦ Useful for gathering large samples of quantitative data from hard-to-reach and hidden populations◦ No sampling frame◦ Allows participants to remain anonymous◦ Peers recruit their peers (stigma, discrimination and lack of trust)
◦ Has already been used successfully used in several countries to sample A/YKP◦ When analyzed correctly, provides representative findings about the network of the
population sampled◦ Manuals and tools available to help you◦ Free computer software available
Malekinejad M, et al. Using respondent-driven sampling methodology for HIV biological and behavioral surveillance in international settings: A systematic review. AIDS and Behavior. 2008.12(Suppl 1): 105-130. Johnston LG, Malekinejad M, Rifkin MR, et al. Implementation challenges to using respondent-driven sampling methodology for HIV biological and behavioral surveillance: Field experiences in international settings. AIDS and Behavior. 2008.12(Suppl 1): 131-141.
RDS OVERVIEW Basics and Challenges
Questions to ask yourself before initiating RDS
◦ Is the population of interest socially networked (i.e., they know each other as part of that population)?
◦ Can you find a small number of persons who are part of the population?
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RDS Basicso Is both a sampling and analysis method
A big challenge for those developing RDS is to match the estimators to the sampling design assumptions
o Type of chain referral sampling method to reach hidden populationso Begin with a set of ‘seeds’o Seeds recruit peers, who recruit peers, etc.o Recruits are linked by coupons with unique identifying numberso Recruitment is limited through a minimum set of couponso Incentives provided for completed survey and for each successful recruit
Typical steps in an RDS survey
Enrollment (valid coupon,
screening, consent)
Interview
Optional: Biological testing for
HIV and STI (pre and post
test counseling)
Coupon explanation, provision of
coupons, incentive
Enrollment
Interview
Biological Testing
Coupon Explanation
Incentive Payment
Recruitment Management
Recruitment Management (2)
RDS Assumptionso For most estimators, RDS is heavily assumption driven:
First order Markov Process (i.e., sampling occurs with replacement, sample becomes independent from the seeds)
Respondents know one another as members of the target population (and these are reciprocal)
Respondents are linked by a network composed of a single component Respondents can accurately report their personal network size Peer recruitment is a random selection from the recruiter’s network Each respondent recruits a single peer
RDS required datao Must collect each participant’s social network sizeo Must collect information about who recruited whom
The importance of social networks in RDSo A participant’s social network size sets up the probability of someone being selected into the studyo Must include all of the criteria used in eligibilityo Only members of a participant’s social network should be recruited
into studyo Analysis is based on each social network member having an equal
probability of being included in the study.oAdapt the question for A/KYP
Where to get answers during formative assessment?
◦ Go to A/YKP◦ Find leaders within the A/YKP target population ◦ Talk to organizations working with A/YKP◦ Talk to gate keepers who may be involved with A/YKP
What kinds of information should you get during formative assessment?
o Network structure, characteristics of the populationo Logistics, acceptability, identification of seeds
Selecting ‘good’ seeds to start your study◦ Seeds are non-randomly selected members of the target
population who◦ Are well regarded by their peers◦ Have large social networks and know diverse types of people◦ Can communicate well ◦ Have some interest in the purpose of the survey
Incentives◦ Find out the legal restrictions are about giving incentives to minors
during research◦ Incentives are usually monetary but other types of incentives are fine◦ Find out what the population wants
CouponsoProvide information about the survey
(hours, location, benefits, etc.) oTrack recruitment progress oManage incentive payments oLink information about recruits and their
recruiters through the ID numberingoAllows participants to be anonymous
AnalysisSoftware programs are available for free
Available at www.hpmrg.org Available at www.respondentdrivensampling.org
RDS strengths and challenges
StrengthsRepresentativeness Efficient for hard to reach populationsManuals and tools available Peer recruit peers No mapping neededAllows for anonymityFree computer software available
Challenges Can be difficult to verify group
membership Uses incentives Difficult to deal with selective non-
response bias Analysis is challenged and
challenging Relies on numerous assumptions
Extra formative research Assess social networksRDS logistics and acceptanceIdentify seedsMobility of A/YKP
Simple coupon designs (pictures)Modified network size questionA/YKP appropriate incentivesToys and activities in waiting room (one staff member)What to do with family members/friends who want to go to interview site
Special Issues: RDS among A/YKP
Include social worker with specialization in A/YKP at interview site Conduct community meetings and involvement of organizations, concerned adults who may or may not be parents or guardiansQuestionnaire design-PILOT A/YKP of 14 years interpret questions differently than A/YKP of 21
yearsThink about communications with policeEthical considerations
Special Issues for A/YKP in any sampling method
Resources Johnston, L. G. Introduction to Respondent Driven Sampling. 2013. Geneva, Switzerland. http://applications.emro.who.int/dsaf/EMRPUB_2013_EN_1539.pdf
NetDraw and RDS Analyst Software Manual. http://applications.emro.who.int/dsaf/EMRPUB_2014_EN_1686.pdf?ua=1
www.hpmrg.org (RDS Analyst Software)
www.respondentdrivensampling.org (RDSAT, references, RDS materials)
www.lisagjohnston.com (resource materials, journal articles, etc.)
Young Key Populations at Higher Risk of HIV in Asia and the Pacific: Making the case with Strategic Information. http://www.unicef.org/eapro/Young_key_populations_at_high_risk_of_HIV_in_Asia_Pacific.pdf
Thank You