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Sampling Adolescents/Young Key Populations (A/YKP) at Risk of HIV Exposure Using Respondent Driven Sampling (RDS). Lisa g. Johnston WWW.lisagjohnston.com, lsjohnston.global@gmail.Com University of California, san Francisco Tulane university, new Orleans. Outline.
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Sampling Adolescents/Young Key Populations (A/YKP) at Risk of HIV Exposure Using Respondent Driven Sampling (RDS) Lisa g. Johnston WWW.lisagjohnston.com, lsjohnston.global@gmail.Com University of California, san Francisco Tulane university, new Orleans
Outline • Why is RDS superior for sampling A/YKP? • RDS Overview • RDS Challenges • RDS 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?
RDS Basics • Is both a sampling and analysis method • A big challenge for those developing RDS is to match the estimators to the sampling design assumptions • Type of chain referral sampling method to reach hidden populations • Begin with a set of ‘seeds’ • Seeds recruit peers, who recruit peers, etc. • Recruits are linked by coupons with unique identifying numbers • Recruitment is limited through a minimum set of coupons • Incentives provided for completed survey and for each successful recruit
RDS Assumptions • 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 data • Must collect each participant’s social network size • Must collect information about who recruited whom
The importance of social networks in RDS • A participant’s social network size sets up the probability of someone being selected into the study • Must include all of the criteria used in eligibility • Only members of a participant’s social network should be recruited into study • Analysis is based on each social network member having an equal probability of being included in the study. • Adapt 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? • Network structure, characteristics of the population • 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
Coupons • Provide information about the survey (hours, location, benefits, etc.) • Track recruitment progress • Manage incentive payments • Link information about recruits and their recruiters through the ID numbering • Allows participants to be anonymous
Analysis Software programs are available for free Available at www.hpmrg.org Available at www.respondentdrivensampling.org
RDS strengths and challenges 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 Strengths • Representativeness • Efficient for hard to reach populations • Manuals and tools available • Peer recruit peers • No mapping needed • Allows for anonymity • Free computer software available
Special Issues: RDS among A/YKP • Extra formative research • Assess social networks • RDS logistics and acceptance • Identify seeds • Mobility of A/YKP • Simple coupon designs (pictures) • Modified network size question • A/YKP appropriate incentives • Toys and activities in waiting room (one staff member) • What to do with family members/friends who want to go to interview site
Special Issues for A/YKP in any sampling method • 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 guardians • Questionnaire design-PILOT • A/YKP of 14 years interpret questions differently than A/YKP of 21 years • Think about communications with police • Ethical considerations
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