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RDS Methods

This page lists in chronological order publications concerning Respondent Driven Sampling Methods. 

Explanation of Abbreviations

 Sampling methods:  Populations:
 RDS - Respondent Driven Sampling PWID/IDU - People who Inject Drugs/Injecting Drug Users
 SRS - Simple Random Sampling  FSW - Female Sex Workers
 TLS - Time Location Sampling  MSM - Men who have Sex with Men
 IFS -  Chain referral Sampling 
 MTF - Male-to-Female Transgender persons
          using Indigenous Field workers
 HRH - High Risk Heterosexual men 


KeywordsPopulation Location Year
Diagnostics
MSM, FSW and DU
Dominican Republic  
Title
Diagnostics for Respondent-Driven Sampling
AuthorsGile KJ, Johnston LG, Salganik MJ
Published inJournal of the Royal Statistical Society. Under review.
Abstract

Respondent-driven sampling (RDS) is a widely used method for sampling from hard-to-reach human populations, especially groups most at-risk for HIV/AIDS. Data are collected through a peer-referral process in which current sample members harness existing social networks to recruit additional sample members. RDS has proven to be a practical method of data collection in many difficult settings and has been adopted by leading public health organizations around the world. Unfortunately, inference from RDS data requires many strong assumptions because the sampling design is partially beyond the control of the researcher and not fully observable. In this paper, we introduce diagnostic tools for most of the assumptions underlying RDS inference. We also apply these diagnostics in a case study of 12 populations at increased risk for HIV/AIDS. These diagnostics empower researchers to better understand their RDS data as well as to encourage future statistical research on RDS sampling and inference.


Language
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KeywordsPopulation Location Year
RDS Comparison
PWID
Lithuania 2014 
Title
A simulative comparison of respondent driven sampling with incentivized snowball sampling - the "strudel effect"
AuthorsGyarmathy AV, Johnston LG, Caplinskiene I, Caplinskas S, Latkin CA
Published inDrug and Alcohol Dependence. In press.
Abstract

Respondent driven sampling (RDS) and Incentivized Snowball Sampling (ISS) are two sampling methods that are commonly used to reach people who inject drugs (PWID). We generated a set of simulated RDS samples on an actual sociometric ISS sample of PWID in Vilnius, Lithuania (“original sample”) to assess if the simulated RDS estimators were statistically significantly different from the original ISS sample prevalences for HIV (9.8%), Hepatitis A (43.6%), Hepatitis B (Anti-HBc 43.9% and HBsAg 3.4%), Hepatitis C (87.5%), syphilis (6.8%) and Chlamydia (8.8%) infections and for selected behavioral risk characteristics.


The original sample consisted of a large component of 249 people (83% of the sample) and 13 smaller components with 1 to 12 individuals. Generally, as long as all the seeds were recruited from the large component of the original sample, the simulation samples simply recreated the large component. There were no significant differences between the large component and the entire original sample regarding the characteristic of interest. Altogether 99.2% of 360 simulation sample point estimates was within the confidence interval of the original prevalence values for the variables of interest.


When population characteristics are reflected in large network components that dominate the population, RDS and ISS may produce samples that have statistically non-different prevalence values, even though some isolated network components may be under-sampled and/or statistically significantly different from the main groups. This so-called “strudel effect” is discussed in the paper. 


Language
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KeywordsPopulation Location Year
RDS/TLS Review
MSM, FSW and PWID/IDU
Worldwide 2014 
Title
Epidemiological Challenges to the Assessment of HIV Burdens among key populations: respondent driven sampling, time location sampling and demographic and health surveys
AuthorsSabin K, Johnston LG
Published inCurrent Opinion in HIV and AIDS. In press.

Abstract

Measuring the burden of HIV among key populations is subject to many challenges. Sufficient quantities of valid HIV prevalence and programme coverage data are required to effectively respond to the epidemic.

Innovative use of prostate specific antigen to validate exposure to unprotected sex provides confirmation of condom use. A new weighting scheme based on frequency of venue attendance for time location samples should improve validity of data obtained with this method. Two new proportion estimators, new diagnostic methods, a new population size estimator and new analysis software will provide more robust results from respondent driven sampling.

Analytical advances have improved the potential quality of results from surveys using time location and respondent driven sampling. However, data from sufficient numbers of sites over sufficient number of years are still needed to provide clear national pictures of distribution and trends of HIV infection.

Language
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Keywords Population  Location  Year
RDS Design Effects PWID/IDU, FSW, MSM, MTF  Peru, United States, China, South Africa, Mauritius, Ukraine 2013 
Title
An empirical examination of Respondent Driven Sampling design effects 
among HIV risk groups from studies conducted around the world
Authors Johnston LG, Chen AH, Silva-Santisteban A, Raymond FH.
Published in AIDS and Behavior. 2013. 17(6):2202-10.
Abstract For studies using respondent driven sampling (RDS), the current practice of collecting a sample twice as large as that used in simple random sampling (SRS) (i.e. design effect of two) may not be sufficient. This paper provides empirical evidence of sample-to-sample variability in design effects using data from nine studies in six countries among injecting drug users, female sex workers, men who have sex with men and male-to-female transgender (MTF) persons.

We computed the design effect as the variance under RDS divided by the variance under SRS for a broad range of demographic and behavioral variables in each study. We also estimated several measures for each variable in each study that we hypothesized might be related to design effect: the number of waves needed for equilibrium, homophily, and mean network size.

Design effects for all studies ranged from 1.2 to 5.9. Mean design effects among all studies ranged from 1.5 to 3.7. A particularly high design effect was found for employment status (design effect of 5.9) of MTF in Peru. This may be explained by a “bottleneck”—defined as the occurrence of a relatively small number of recruitment ties between two groups in the population.

A design effect of two for RDS studies may not be sufficient. Since the mean design effect across all studies was 2.33, an effect slightly above two may be adequate, however, an effect closer to three or four would be ideal.
Language
Download Johnston design effect 2013.pdf


KeywordsPopulation Location Year
Recruitment and point estimationMale heads of households
Uganda 2013 
Title
Respondent Driven Sampling: Determinants of Recruitment and a Method to Improve Point Estimation
AuthorsMcCreesh N, Copas A, Seeley J, Johnston LG, et al.
Published inPLoS ONE. 2013. 8(10):e78402.
AbstractRespondent-driven sampling (RDS) is a variant of a link-tracing design intended for generating unbiased estimates of the composition of hidden populations that typically involves giving participants several coupons to recruit their peers into the study. RDS may generate biased estimates if coupons are distributed non-randomly or if potential recruits present for interview non-randomly. We explore if biases detected in an RDS study were due to either of these mechanisms, and propose and apply weights to reduce bias due to non-random presentation for interview.

Using data from the total population, and the population to whom recruiters offered their coupons, we explored how age and socioeconomic status were associated with being offered a coupon, and, if offered a coupon, with presenting for interview. Population proportions were estimated by weighting by the assumed inverse probabilities of being offered a coupon (as in existing RDS methods), and also of presentation for interview if offered a coupon by age and socioeconomic status group.

Younger men were under-recruited primarily because they were less likely to be offered coupons. The under-recruitment of higher socioeconomic status men was due in part to them being less likely to present for interview. Consistent with these findings, weighting for non-random presentation for interview by age and socioeconomic status group greatly improved the estimate of the proportion of men in the lowest socioeconomic group, reducing the root-mean-squared error of RDS estimates of socioeconomic status by 38%, but had little effect on estimates for age. The weighting also improved estimates for tribe and religion (reducing root-mean-squared-errors by 19–29%), but had little effect for sexual activity or HIV status.Conclusions

Data collected from recruiters on the characteristics of men to whom they offered coupons may be used to reduce bias in RDS studies. Further evaluation of this new method is required.

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Keywords Population  Location  Year
Population size estimation using the Service Multiplier Method     MSM, FSW and PWID/IDU  Mauritius, Papua New Guinea, Thailand, United States 2013 
Title
Incorporating the service multiplier method in respondent driven sampling surveys to estimate the size of hidden and hard-to-reach populations: Case studies from around the world
Authors Johnston LG, Prybylski D, Raymond HF, Mirzazadeh A, Manopaiboon C, McFarland W.
Published in Sexually Transmitted Diseases. 2013. 40(4):304-10
Abstract Estimating the sizes of populations at highest risk for HIV is essential for developing and monitoring effective HIV prevention and treatment programs. We provide several country examples of how service multiplier methods have been used in respondent driven sampling (RDS) surveys and provide guidance on how to maximize this method’s utility.

Population size estimates were conducted in four countries (Mauritius-injection drug users [IDU] and female sex workers [FSW]; Papua New Guinea-FSW and men who have sex with men [MSM]; Thailand-IDU; United States-IDU) using adjusted proportions of population members reporting attending a service, project or study listed in an RDS survey and the estimated total number of population members who visited one of the listed services, projects or studies collected from the providers.

The median population size estimates were 8,866 for IDU and 667 for FSW in Mauritius. Median point estimates for FSW were 4,190 in Port Moresby and 8,712 in Goroka, Papua New Guinea and 2,126 for MSM in Port Moresby and 4,200 for IDU in Bangkok, Thailand. Median estimates for IDU were 1,050 in Chiang Mai, Thailand, and in San Francisco 15,789 in 2005 and 15,554 in 2009.

Our estimates for almost all groups in each country fall within the range of other regional and national estimates indicating that the service multiplier method, assuming all assumptions are met, can produce informative estimates. We suggest using multiple multipliers whenever possible, garnering program data from the widest possible range of services, projects and studies. A median of several estimates is likely more robust to potential biases than a single estimate.
Language
Download Johnston et al. Incorporating multiplier method in RDS sureys for PSE - STD 40-4-2013.pdf

Keywords Population  Location  Year
Review of RDS MSM, FSW and PWID/IDU  Latin America and the Caribbean 2013
Title
Respondent Driven Sampling for HIV Biological and Behavioral Surveillance in Latin America and the Caribbean
Authors Montealegre JR, Johnston LG, Murrill C, Monterroso E.
Published in AIDS and Behavior. 2013. 17(7); 2313-2340
Abstract Since 2005, respondent driven sampling (RDS) has been widely used for HIV biological and behavioral surveillance surveys (BBSS) in Latin America and the Caribbean (LAC).

In this manuscript, we provide a focused review of RDS among hard-to-reach high-risk populations in LAC and describe their principal operational, design, and analytical challenges and considerations. We reviewed published and unpublished reports, protocols, and manuscripts for RDS studies conducted in LAC between January 1, 2005 and December 31, 2011. We abstracted key operational information and generated summary statistics across all studies.

Between 2005 and 2011, 87 RDS studies were conducted in 15 countries in LAC (68% in South America, 18% in Mexico and Central America, and 14% in the Caribbean). The target populations were primarily men who have sex with men (43%), sex workers (29%), and drug users (26%). Study challenges included establishing clear eligibility criteria, measuring social network sizes, collecting specimens for biological testing, among others.  

Most of the reviewed studies are the first in their respective countries to collect data on hard-to-reach populations and the first attempt to use a probability-based sampling method. These RDS studies allowed researchers and public health practitioners in LAC to access hard-to-reach HIV high-risk populations and collect valuable data on the prevalence of HIV and other infections, as well as related risk behaviors.
Language
Download RDS in LAC.pdf

Keywords Population  Location  Year
The role of location and distance Male heads of households Uganda 2011
Title
Evaluation of the role of location and distance in recruitment in respondent-driven sampling
Authors McCreesh N, Johnston LG, Copas A, Sonnenberg P, Seeley J, Hayes RJ, Frost SDW, White RG.
Published in International Journal of Health Geographics. 2011. 10:56
Abstract Respondent-driven sampling (RDS) is an increasingly widely used variant of a link tracing design for recruiting hidden populations. The role of the spatial distribution of the target population has not been robustly examined for RDS.

We examine patterns of recruitment by location, and how they may have biased an RDS study findings. Total-population data were available on a range of characteristics on a population of 2402 male household-heads from an open cohort of 25 villages in rural Uganda. The locations of households were known a-priori. An RDS survey was carried out in this population, employing current RDS methods of sampling and statistical inference.

There was little heterogeneity in the population by location. Data suggested more distant contacts were less likely to be reported, and therefore recruited, but if reported more distant contacts were as likely as closer contacts to be recruited. There was no evidence that closer proximity to a village meeting place was associated with probability of being recruited, however it was associated with a higher probability of recruiting a larger number of recruits. People living closer to an interview site were more likely to be recruited. Household location affected the overall probability of recruitment, and the probability of recruitment by a specific recruiter.

Patterns of recruitment do not appear to have greatly biased estimates in this study. The observed patterns could result in bias in more geographically heterogeneous populations. Care is required in RDS studies when choosing the network size question and interview site location(s).
Language
Downloads Geographic_RDSUganda.pdf 


Keywords Population  Location  Year
Evaluation of RDS by comparison with total population data  Male heads of households Uganda 2012
Title
Evaluation of Respondent-driven Sampling
Authors McCreesh N, Frost SDW, Seeley J, Katongole J, Tarsh MN, Ndunguse R, Jichi F, Lunel NL, Maher D, Johnston LG, Sonnenberg P, Copas A, Hayes RJ, White RG.
Published in Epidemiology 2012. 23: 138–147
Abstract Respondent-driven sampling (RDS) is a novel variant of link-tracing sampling for estimating the characteristics of hard-to reach groups, such as HIV prevalence in sex workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown.

We evaluated RDS by comparing estimates from a RDS survey with total population data. Total population data on age, tribe, religion, socioeconomic status, sexual activity, and HIV status were available on a population of 2402 male household heads from an open cohort in rural Uganda. A RDS survey was carried out in this population, using current methods of sampling (RDS sample) and statistical inference (RDS estimates).

Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). We recruited 927 household heads. Full and small RDS samples were largely representative of the total population, but both samples underrepresented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status.

RDS statistical inference methods failed to reduce these biases. Only 31%–37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%–74% of respondent-driven sampling bootstrap 95% confidence intervals included the population proportion. RDS produced a generally representative sample of this well-connected nonhidden population. However, current RDS inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a RDS survey is unresolved.

RDS should be regarded as a (potentially superior) form of convenience sampling method, and caution is required when interpreting findings based on the sampling method.
Language
Download McCreeshetal,rds,epidemiology2012.pdf

Keywords Population  Location  Year
Using RDS to recruit HRH Men HRH men South Africa 2010
Title
Effectiveness of Respondent-Driven Sampling to Recruit High Risk Heterosexual Men Who Have Multiple Female Sexual Partners: Differences in HIV Prevalence and Sexual Risk Behaviours Measured at Two Time Points
Authors Townsend L, Johnston LG, Fisher A, Mathews C, Yanga Z.
Published in AIDS and Behavior. 2010. 14(6):1330-1339.
Abstract Regular HIV bio-behavioural surveillance surveys (BBSS) among high risk heterosexual (HRH) men who have multiple female sexual partners is needed to monitor HIV prevalence and risk behaviour trends, and to improve the provision and assessment of HIV prevention strategies for this population.

In 2006 and 2008 we used respondent-driven sampling to recruit HRH men and examine differences in HIV prevalence and risk behaviours between the two time points.

In both surveys, the target population had little difficulty in recruiting others from their social networks that were able to sustain the chain referral process. Key variables reached equilibrium within one to six recruitment waves and homophily indices showed neither tendencies to in-group nor out-group preferences.

Between 2006 and 2008 there were significant differences in condom use with main sexual partners; numbers of sexual partners; and alcohol consumption. Further BBSS among this population are needed before more reliable trends can be inferred.
Language
Download RDSOVERTIMEAIDSBehav2010.pdf
   
Keywords Population  Location  Year
Challenges with using RDS MSM, FSW and PWID/IDU International settings 2009
Title
Implementation challenges to using respondent-driven sampling methodology for HIV biological and behavioral surveillance: Field experiences in international settings
Authors Johnston LG, Malekinejad M, Rifkin MR, Rutherford GW, Kendall C.
Published in AIDS and Behavior. 2009.12(Suppl 1): 131-141.
Abstract Using respondent-driven sampling (RDS), we gathered data from 128 HIV surveillance studies conducted outside the United States through October 1, 2007.

We examined predictors of poor study outcomes, reviewed operational, design and analytical challenges associated with conducting RDS in international settings and offer recommendations to improve HIV surveillance. We explored factors for poor study outcomes using differences in mean sample size ratios (recruited/calculated sample size) as the outcome variable.

Ninety-two percent of studies reported both calculated and recruited sample sizes. Studies of injecting drug users had a higher sample size ratio compared with other risk groups. Study challenges included appropriately defining eligibility criteria, structuring social network size questions, selecting design effects and conducting statistical analysis.

As RDS is increasingly used for HIV surveillance, it is important to learn from past practical, theoretical and analytical challenges to maximize the utility of this method.
Language
Download SamplingChallengesRDSJohnstonetalAIBE2008.pdf

Keywords Population  Location  Year
Review of RDS in international settings MSM, FSW and PWID/IDU International settings 2008
Title
Using respondent-driven sampling methodology for HIV biological and behavioral surveillance in international settings: A systematic review
Authors Malekinejad M, Johnston LG, Kendall C, Kerr LRFS, Rifkin MR, Rutherford GW.
Published in AIDS and Behavior. 2008.12(Suppl 1): 105-130.
Abstract We reviewed HIV biological and behavioral surveillance surveys that used respondent-driven sampling (RDS) to study most-at-risk populations in international settings.

We conducted bibliographical searches, contacted key informants and abstracted data from RDS studies that were completed by October 1, 2007, fulfilled RDS methodological requirements and conducted outside the United States. We identified 123 eligible studies; 59 from Europe, 40 from Asia and the Pacific, 14 from Latin America and the Caribbean, 7 from Africa and 3 from Oceania.

Studies collectively recruited 32,298 participants between 2003 and 2007; 53% of studies were conducted among drug users (DU), which generally recruited participants faster compare with sex workers. All but 13 studies reached ≥90% of their intended sample size, and six studies failed to reach equilibrium for key variables.

This review showed that RDS is an effective technique to sample most-at-risk populations for HIV biological and behavioral surveys when implemented appropriately.
Language
Download SystematicReviewRDSMalekinejadetalAIBE2009.pdf

Keywords Population  Location  Year
Presentation of TLS and RDS MSM, FSW and PWID/IDU Worldwide
2010
Title
Update for sampling most-at-risk and hidden populations for HIV biological and behavioral surveillance
Authors Johnston LG, Sabin K, Prybylski.
Published in Journal of HIV/AIDS Surveillance & Epidemiology. 2010.
Abstract Two meetings, the first one in 2004 in Addis Ababa, Ethiopia, and the second in 2009 in Bangkok, Thailand, on “New Strategies for HIV/AIDS Surveillance in Resource-Constrained Countries” were held through collaborative efforts of UNAIDS, WHO, CDC-GAP and USAID. These meetings gathered technical staff from around the world, to share new strategies, advances and challenges in HIV biological and behavioral surveillance implementation in resource-constrained countries.

The first meeting included discussions on recently developed sampling methods to improve data collected from HIV high-risk populations: time location sampling (TLS) and respondent driven sampling (RDS). With the widening use of the TLS and RDS methodologies over time, there have been important technical advances and ongoing methodological challenges not yet formally disseminated.

This paper presents some of the key findings of the second meeting and highlights the status of these sampling methods, including challenges and recommendations, of using TLS and RDS with most-at-risk populations for HIV biological and behavioral surveillance.
Language
Download JohnstonRDSupdateJHASE2010.pdf

Keywords Population  Location  Year
Sampling with RDS MSM, FSW and PWID/IDU Worldwide
2010
Title
Sampling hard-to-reach populations with respondent driven sampling (In English) or Échantillonnage déterminé selon les répondants pour les populations difficiles à joindre (in French) 
Authors Johnston LG, Sabin K.
Published in Methodological Innovations Online. 2010. 5(2) 38-48.
Abstract Cost effective and targeted prevention, intervention and treatment programs for hard-to-reach populations at risk for HIV and other infections rely on the collection of quality data through biological and behavioral surveillance surveys (BBSS).

Over the past decade, there has been a global expansion of BBSS to measure the prevalence of HIV and other infections, and related risk behaviors among injecting drug users, males who have sex with males, and female sex workers. However, a major challenge to sampling these hard-to-reach populations is that they are usually stigmatised and/or practice illegal behaviors which, in turn, make them difficult to access and unwilling to participate in research efforts.

Over the past decade, respondent driven sampling (RDS) has become recognised as a viable option for rigorous sampling of hard-to-reach populations.

This paper introduces RDS methods and describes some of the advantages and challenges to implementing and analysing surveys that use RDS. 
Language  
English JohnstonSabinRDSMethodologicalInnovationsOnline2010ENG.pdf
French JohnstonSabinRDSMethodologicalInnovationsOnline2010FR.pdf

Keywords Population  Location  Year
Evaluating RDS FSW and PWID/IDU Estonia 2010
Title
Evaluating recruitment among Female Sex Workers and Injecting Drug Users at Risk for HIV using Respondent Driven Sampling in Estonia
Authors Uusküla A, Johnston LG, Raag M, Trummal A, Talu A, Des Jarlais DC.
Published in Journal of Urban Health. 2010. 87(2):304-317.
Abstract Few recent publications have highlighted theoretical and methodological challenges using respondent-driven sampling (RDS).

To explore why recruitment with RDS may work in some populations and not in others, we assess the implementation of RDS to recruit female sex workers (FSWs) and injection drug users (IDUs) into a human immunodeficiency virus biological and risk behavior survey in Tallinn, Estonia.

Recruitment of FSWs was slower and more challenging than that of IDUs. The IDU study recruited 350 participants within 7 weeks, while the FSW study recruited 227 participants over 28 weeks. Implementation modifications that did not negatively impact key RDS theoretical and methodological requirements were used to improve recruitment during the FSW study.

We recommend that all RDS studies include a formative research process to involve the participation of target populations and key persons associated with these populations in the study planning and throughout the implementation processes to improve recruitment from the outset and to respond to poor recruitment during data collection.
Download
EstoniaIDUFSWRDSUuskulaetalJUH2010.pdf
https://www.researchgate.net/publication/41405901





Keywords Population  Location  Year
Formative research to optimize RDS surveys MSM, FSW and PWID/IDU Bosnia-Herzegovina, Thailand, Montenegro and Eastern Caribbean 2010
Title
Formative research to optimize Respondent Driven Sampling surveys among hard to reach populations in HIV behavioral and biological surveillance: Lessons learned from four case studies
Authors Johnston LG, Whitehead S, Simic M, Kendall, C.
Published in AIDS Care. 2010. 22(6):784-92.
Abstract Respondent driven sampling (RDS) is widely adopted as a method to assess HIV and other sexually transmitted infection prevalence and risk factors among hard-to-reach populations. Failures to properly implement RDS in several settings could potentially have been avoided had formative research been conducted. However, to date there is no published literature addressing the use of formative research in preparing for RDS studies.

This paper uses examples from Banja Luka, Bosnia & Herzegovina; Bangkok, Thailand; Podgorica, Montenegro; and St. Vincent’s & Grenadine Islands, Eastern Caribbean; among populations of men who have sex with men, female sex workers, and injecting drug users to describe how formative research was used to plan, implement and predict outcomes of RDS surveys and to provide a template of RDS-specific questions for conducting formative research in preparation for RDS surveys.

We outline case studies to illustrate how formative research may help researchers to determine whether RDS methodology is appropriate for a particular population and socio-cultural context, and to decide on implementation details that lead to successful study outcomes.
Download JohnstonetalFormativeRschRDSAIDSCare2009.pdf
https://www.researchgate.net/publication/44597358



Keywords Population  Location  Year
Internet sampling versus RDS MSM Estonia 2009
Title
Efficacy of convenience sampling through the internet versus respondent driven sampling among males who have sex with males in Tallinn and Harju County, Estonia: Challenges reaching a hidden population
Authors Johnston LG, Trummal A, Lõhmus L, Ravalepik A.
Published in AIDS Care. 2009. 21 (9): 1195-1202.
Abstract This paper examines challenges obtaining representative samples of males who have sex with males (MSM) in Estonia and provides descriptive HIV behavioral data gathered from four cross-sectional surveys; three using the internet, and one using respondent driven sampling (RDS) to recruit MSM in Tallinn and Harju County.

Estonian MSM were sampled between March and May in 2004 (n=193), August and November in 2005 (n=146) and September and December in 2007 (n=238) using internet websites. MSM in Tallinn and Harju County were sampled between April and June in 2007 (n=59) using RDS.

Recruitment of MSM using RDS did not acquire the calculated sample size. The RDS study reached a less diverse group of MSM than did the internet studies which recruited a larger proportion of MSM who were older, bisexual, having female sexual partners during the last six months, and unlikely to have been tested for HIV.

The findings and observations presented in this paper could inform researchers in Estonia, and the region, about the efficacy of and socio-cultural challenges to sampling MSM to collect HIV biological and/or behavioral data.
Download SamplingRDSvs.InternetMSMJohnstonetalAIDSCARE2009.pdf
https://www.researchgate.net/publication/40732270




Keywords Population  Location  Year
Comparison of RDS, TLS and Snowball Sampling MSM Brazil 2008
Title
An empirical comparison of respondent-driven sampling, time location sampling, and snowball sampling for behavioral surveillance in men who have sex with men, Fortaleza, Brazil
Authors Kendall C, Kerr L, Gondim CC, Werneck GL, Macena R, Pontes M, Johnston LG, Sabin K, McFarland, W.
Published in AIDS and Behavior. 2008. 12(Suppl 1): 97-104.
Abstract Obtaining samples of populations at risk for HIV challenges surveillance, prevention planning, and evaluation. Methods used include snowball sampling, time location sampling (TLS), and respondent-driven sampling (RDS). Few studies have made side-by-side comparisons to assess their relative advantages.

We compared snowball, TLS, and RDS surveys of men who have sex with men (MSM) in Forteleza, Brazil, with a focus on the socio-economic status (SES) and risk behaviors of the samples to each other, to known AIDS cases and to the general population.

RDS produced a sample with wider inclusion of lower SES than snowball sampling or TLS-a finding of health significance given the majority of AIDS cases reported among MSM in the state were low SES. RDS also achieved the sample size faster and at lower cost. For reasons of inclusion and cost-efficiency, RDS is sampling methodology of choice for HIV surveillance of MSM in Fortaleza.
Download EmpiricalComparisonBrazilKendalletal.AIBE2008.pdf
https://www.researchgate.net/publication/51393171




Keywords Population  Location  Year
Effectiveness of RDS for recruiting MSM Bangladesh 2007
Title
The effectiveness of respondent driven sampling for recruiting males who have sex with males in Dhaka, Bangladesh: A pilot study
Authors Johnston LG, Khanam R, Reza M, Khan SI, Banu S, Alam MS, Rahman M, Azim T.
Published in AIDS and Behavior. 2007. 2(2): 294-304.
Abstract This paper evaluates the effectiveness of respondent driven sampling (RDS) to sample males who have sex with males (MSM) in Dhaka, Bangladesh. A major objective for conducting this survey was to determine whether RDS can be a viable sampling method for future routine serologic and behavioral surveillance of MSM as well as other socially networked, hard to reach populations in Bangladesh.

We assessed the feasibility of RDS (survey duration; MSM social network properties; number and types of initial recruits) to recruit a diverse group of MSM, the efficacy of an innovative technique (systematic coupon reduction) to manage the implementation and completion of the RDS recruitment process and reasons why MSM participated or did not participate.

The findings provide useful information for improving RDS field techniques and demonstrate that RDS is an effective sampling method for recruiting diverse groups of MSM to participate in HIV related serologic and behavioral surveys in Dhaka.
Download BangladeshMSMAIDSbeh_2007.pdf
https://www.researchgate.net/publication/6126572




Keywords Population  Location  Year
Effectiveness of RDS for recruiting FSW Vietnam 2006
Title
Effectiveness of respondent-driven sampling to recruit female sex workers in two cities in Vietnam
Authors Johnston LG, Sabin K, Hien MT, Huong PT.
Published in Journal of Urban Health. 2006. 83 (Suppl 7): 16-28.
Abstract Respondent driven sampling (RDS) is a relatively new method to sample hard-to-reach populations. Until this study, female sex workers (FSWs) in Vietnam were sampled using a variety of methods, including time location sampling (TLS), which may not access the more hidden types of FSWs.

This paper presents an analysis from an HIV biological and behavioral surveillance survey to assess the feasibility and effectiveness of RDS to sample FSWs, to determine if RDS can reach otherwise inaccessible FSWs in Vietnam and to compare RDS findings of HIV risk factors with a theoretical TLS.

Through face-to-face interviews with FSWs in Ho Chi Minh City (HCMC) and Hai Phong (HP), data were collected about the venues where they most often solicit their clients. These data were used to create three variables to assess whether FSWs solicit their clients in locations that are visible, semi-visible and non- visible.

For this analysis, the visible group simulates a sample captured using TLS. Survey results in HIV prevalence and related risk factors and service utilization, adjusted for sampling methodology, were compared across each of the three FSW visibility groups to assess potential bias in TLS relative to RDS.
Download TLSRDSFSWsVietnamJohnstonetalJUH2006.pdf
https://www.researchgate.net/publication/6762816


  

Keywords Population  Location  Year
Appropriateness of using RDS FSW Russia, Serbia and Montenegro 2006
Title
Exploring Barriers to 'Respondent Driven Sampling' in Sex Worker and Drug-Injecting Sex Worker Populations in Eastern Europe
Authors Simic M, Johnston LG, Platt L, Baros S, Andjelkovic V, Rhodes T.
Published in Journal of Urban Health. 2006. 83 (Suppl 7):6-15.
Abstract Respondent driven sampling (RDS) has been used in several countries to sample injecting drug users, sex workers (SWs) and men who have sex with men and as a means of collecting behavioural and biological health data.

We report on the use of RDS in three separate studies conducted among SWs between 2004 and 2005 in the Russian Federation, Serbia, and Montenegro.

Findings suggest that there are limitations associated with the use of RDS in SW populations in these regions. Findings highlight three main factors that merit further investigation as a means of assessing the feasibility and appropriateness of RDS in this high risk population: the network characteristics of SWs; the appropriate level of participant incentives; and lack of service contact. The highly controlled and hidden nature of SW organizations and weak SW social networks in the region can combine to undermine assumptions underpinning the feasibility of RDS approaches and potentially severely limit recruitment.

We discuss the implications of these findings for recruitment and the use of monetary and non-monetary incentives in future RDS studies of SW populations in Eastern Europe.
Download EasternEuropeSimicetalJUH2006.pdf
https://www.researchgate.net/publication/6689030


  

Keywords Population  Location  Year
Comparing RDS and IFS PWID/IDU Russia, Estonia 2006
Title
Methods to recruit hard-to-reach groups: Comparing two chain referral sampling methods of recruiting injecting drug users (IDU) across nine studies in Russia and Estonia
Authors Platt L, Wall M, Rhodes T, Judd A, Hickman M, Johnston LG, Sarang A, Bobrova N.
Published in Journal of Urban Health. 2006. 83 (Suppl 7):28-34.
Abstract Evidence suggests rapid diffusion of injecting drug use and associated outbreaks of HIV among injecting drug users (IDUs) in the Russian Federation and Eastern Europe. There remains a need for research among non-treatment and community-recruited samples of IDUs to better estimate the dynamics of HIV transmission and to improve treatment and health services access.

We compare two sampling methodologies "respondent-driven sampling" (RDS) and chain referral sampling using "indigenous field workers" (IFS) to investigate the relative effectiveness of RDS to reach more marginal and hard-to-reach groups and perhaps to include those with the riskiest behaviour around HIV transmission.

We evaluate the relative efficiency of RDS to recruit a lower cost sample in comparison to IFS. We also provide a theoretical comparison of the two approaches. We draw upon nine community-recruited surveys of IDUs undertaken in the Russian Federation and Estonia between 2001 and 2005 that used either IFS or RDS. Sampling effects on the demographic composition and injecting risk behaviours of the samples generated are compared using multivariate analysis.

Our findings suggest that RDS does not appear to recruit more marginalised sections of the IDU community nor those engaging in riskier injecting behaviours in comparison with IFS. RDS appears to have practical advantages over IFS in the implementation of fieldwork in terms of greater recruitment efficiency and safety of field workers, but at a greater cost.

Further research is needed to assess how the practicalities of implementing RDS in the field compromises the requirements mandated by the theoretical guidelines of RDS for adjusting the sample estimates to obtain estimates of the wider IDU population.
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