Evaluation of the role of location and distance in recruitment in respondent-driven sampling.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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).
Department of Infectious Disease Epidemiology, Faculty of Epidemiology & Population Health, London School of Hygiene and Tropical Medicine, UK.
Nicky
N
McCreesh
Lisa G
LG
Johnston
Andrew
A
Copas
Pam
P
Sonnenberg
Janet
J
Seeley
Richard J
RJ
Hayes
Simon D W
SD
Frost
Richard G
RG
White
D015982:Bias; D015331:Cohort Studies; D015340:Epidemiologic Research Design; D006679:HIV Seropositivity / Q000453:epidemiology; D015497:HIV-1; D006801:Humans; D008297:Male; D018579:Patient Selection; D011336:Probability; D012424:Rural Population; D012494:Sampling Studies; D057545:Social Stigma; D011795:Surveys and Questionnaires; D014454:Uganda / Q000453:epidemiology