Respondent driven sampling rds is a networkbased technique for estimating traits in hardtoreach populations, for example, the prevalence of hiv among drug injectors. Imports mass, lpsolve license gpl 2 encoding latin1 needscompilation yes. Participating countries were required to develop their sample design and selection plans. Convenience sampling is a nonprobability sampling technique where subjects are selected because of their convenient accessibility and proximity to the researcher. Respondentdriven sampling rds is a widely used method for sampling from hardtoreach human populations, especially groups most atrisk for hivaids. Relativitys sampling functionality allows you to select of a subset of items from a larger population to qc those items or identify characteristics of the whole population. Novel sampling design for respondent driven sampling mohammad khabbazian1, bret hanlon 2, zoe russek, and karl rohe 1department of electrical and computer engineering, university of wisconsinmadison 2department of statistics, university of wisconsinmadison abstract respondent driven sampling rds is a method of chain referral sampling popular. Stratified random sampling is often very useful, but even if you do not have randomized sampling, stratification can help.
Aug 01, 2011 the judgment that chainreferral sampling is a convenience method was challenged in a series of papers leading to the development of a new method for collecting and analyzing chainreferral data, respondent driven sampling rds. As the sample builds up, enough data are gathered to be useful for research. Sampling gordon lynchi introduction one of the aspects of research design often overlooked by researchers doing fieldwork in the study of religion is the issue of sampling. Respondentdriven sampling rds is an approach to sampling design and analysis which utilizes the networks of social relationships that connect members of the target population, using chainreferral. Rejection sampling consider a distribution over with pdf f assume f is bounded so that basic rejection sampling.
By tracing the links in the underlying social network, the process exploits the social structure to expand the sample and reduce its dependence on the initial convenience sample. Workshop on respondentdriven sampling analyst software. Several years after colemans and goodmans development of snowball sampling, what was also termed snowball sampling emerged as a nonprobability approach to. Introduction to sampling distinguishing between a sample and a population simple random sampling step 1. Respondentdriven sampling rds is one method that can be used to reach these. Respondentdriven sampling is a novel variant of linktracing sampling for estimating the characteristics of hardtoreach groups, such as hiv prevalence in sexworkers. A theoretical and practical implementation tutorial on topic. Accepted samples x, y distribute uniformly over the subgraph of fx cs295, spring 2017 shuang zhao 6. One of the most wellknown forms of nonprobability sampling. A simple random samplein which each sampling unit is a collection or cluster, or elements.
Rds sampling will typically oversample participants with many acquaintances. Sampling at 192khz produces a huge burden on the computational processing. If the inline pdf is not rendering correctly, you can download the pdf file here. Data are collected through a peerreferral process in which current sample members harness existing social networks to recruit additional sample members. A theoretical and practical implementation tutorial on. There are several download options, depending on your operating system, and system configuration. Invented by heckathorn in the mid90ies, respondent driven sampling rds heckathorn 1997, equation. Rds augments the referral method by weighting the sample in order to compensate for the initial nonrandom selection, which may lead to the reduction of errors occurring in sampling by the referral method. Johnston lg, whitehead s, simiclawson m, kendall c. They are also usually the easiest designs to implement. Novel sampling design for respondentdriven sampling. The sampling frame is the list from which the sample is selected, so the quality of the sampling frame affects the quality of the sample.
Simple random sampling and systematic sampling simple random sampling and systematic sampling provide the foundation for almost all of the more complex sampling designs based on probability sampling. Respondentdriven sampling should be regarded as a potentially superior form of convenience sampling method, and caution is required when interpreting findings based on the sampling method. Types of sampling probability sampling leaked soccer. Gibbs sampling is based on sampling from conditional distributions of the variables of the posterior. Respondentdriven sampling columbia university mailman. Douglas heckathorn, a professor of sociology at cornell and has been applied to groups ranging from men who have sex with men, injection drug users, children living on the street and jazz musicians. Sample quality know what population it represents unspecified is no good know how cases were selected systemic, chance driven, haphazard sample quality is determined by sample obtained, not by sampling method itself.
For example, to sample x from the joint distribution px px 1x m, where there is no closed form solution for px, but a representation for the conditional distributions is. Respondentdriven sampling rds is a chainreferral method for sampling members of a hidden or hardtoreach population such as sex workers, homeless people, or drug users via their social network. To execute sampling, relativity uses a randomization algorithm called the fisheryates shuffle, which guarantees an efficient and unbiased result. Simple random sampling srs simple random sampling is when we have a full list of everyone in the population, and we randomly choose individuals from the list. Sampling at 192khz produces larger files requiring more storage space and slowing down the transmission. English, russian, spanish, french, chinese, greek and vietnamese. As described in leo goodmans 2011 comment, snowball sampling was developed by coleman 19581959 and goodman 1961 as a means for studying the structure of social networks. Documents in econstor may be saved and copied for your personal and scholarly.
Sequential sampling plot measurement 0 4 8 12 16 20 sample. It is often used in situations where the target population is rare andor stigmatized in the larger population, so that it is prohibitively expensive to contact them through the available frames. Respondentdriven sampling rds is n approach to sampling design and inference in hardtoreach human populations. Presentation by giovanna merli on day 4 of social networks and health workshop at duke university. It is useful when the researcher know little about a group or organisation. Default password for rdscm is password all lowercase rdscm is available six languages. Appendix a illustrates a ranuni method to select stratified samples. For example, an investigator wishing to study students might first sample groups or clusters of students such as classes or dormitories, and then select the fmal sample ofstudents from among clusters. Sampling procedures cover the practice of selecting representative quantities of test material in the field, to evaluate bulk materials.
In recent years rds has been used in more than 120 studies in more than 20 countries and by leading public health organizations, including the centers for disease control and prevention in the united states. By applying some choice procedure to get a smaller subset of units, we. Respondent driven sampling why is bias a particularly big problem here. Workshop on respondent driven sampling analyst software by the hardtoreach population methods research group we are. Respondentdriven sampling is a form of snowball sampling which allows researchers to make estimates about hidden population such as the three groups at highest risk for hivaids. The first step in stratified sampling is to divide the population into subgroups strata based on mutually exclusive criteria. Sample size with non probability sampling methods for. Stratified random sampling and cluster sampling are still probability sampling methods nonprobability methods trade generalizability for logistics probability sampling requires a list of all the units in our population. Thus the sample group is said to grow like a rolling snowball. The principal reasons for using stratified random sampling rather than simple random sampling are as follows. Try to obtain the sample frame in the most automated way possible for ease of sampling. Freedman department of statistics university of california berkeley, ca 94720 the basic idea in sampling is extrapolation from the part to the. How to implement respondentdriven sampling in practice. First, inferences about individuals must rely mainly on the initial sample, since additional individuals found by tracing chains are never found randomly or even with known biases.
It is relatively commonplace for books and articles in the field particularly written from a humanities perspective to present their empirical data as being of self. Respondent driven sampling should be regarded as a potentially superior form of convenience sampling method, and caution is required when interpreting findings based on the sampling method. In addition, adequate information on the frame must be. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. The respondent driven sampling coupon manager rdscm provides a convenient way to keep track of coupons numbers and respondent compensation.
The population is sometimes rather mysteriously called the universe. First developed in 1997 by douglas heckathorn, it is commonly used in hiv research, where groups at high risk of disease exposure are hardtoreach such as sex workers and illicit drug users. Convenience sampling, explorable the subjects are selected just because they are easiest to recruit for the study and the. Respondentdriven sampling analysis tool rdsat version 7. Sampling theory for digital audio by dan lavry, lavry. Respondent driven sampling rds is a chainreferral method for sampling members of a hidden or hardtoreach population such as sex workers, homeless people, or drug users via their social network. In our example, each corporation is a sampling unit of the population. Rds is based on the theory that bias in recruitment is overcome after recruitment proceeds through a sufficiently large number of waves. The balanced bridge sampling system operates with less noise and better linearity than the single diode open loop system. Rds is a type of snowball sampling used for analyzing characteristics of hidden or hardtoreach populations. Pdf respondent driven sampling where we are and where. Respondentdriven sampling rds, introduced by heckathorn 1997, also 2002, 2007, see also salganik and heckathorn, 2004, volz and heckathorn 2008 is an approach to sampling design and inference in hardtoreach populations. Respondent s recruiting serial numbers serial numbers from the coupons the respondent is given to recruit others. The first step in stratified sampling is to divide the population into subgroups strata based on.
Respondent driven sampling rds employs a variant of a linktracing network sampling strategy to collect data from hardtoreach populations. A respondentdriven sampling rds survey was carried out in this. Chainreferral sampling that starts with a limited number of seeds who refer their peers. Chapter 16 introduction to sampling error of means the message of chapter 14 seemed to be that unsatisfactory sampling plans can result in samples that are unrepresentative of the larger population. The simple random sampling approach ensures that every person in the population has the same probability of being selected. Novel sampling design for respondentdriven sampling mohammad khabbazian1, bret hanlon 2, zoe russek, and karl rohe 1department of electrical and computer engineering, university of wisconsinmadison 2department of statistics, university of wisconsinmadison abstract respondentdriven sampling rds is a method of chain referral sampling popular. In the full paper, orss, we develop techniques for sampling from some types of files which are com mon in dbmss. Workshop on respondentdriven sampling analyst software by the hardtoreach population methods research group we are. This is a pdf file of an unedited manuscript that has been accepted. Sequential sampling 8 and ft, is the probability density function for the noncentral tdistribution with degrees of freedom and noncentrality parameter s n 1 0 5 the decision limits are then two parallel lines as shown below. A stratified random sample is one obtained by separating the population elements into nonoverlapping groups, called strata and then selecting a simple random sample from each stratum. In sociology and statistics research, snowball sampling or chain sampling, chainreferral sampling, referral sampling is a nonprobability sampling technique where existing study subjects recruit future subjects from among their acquaintances. Stratified sampling the statistical sampling method called stratified sampling is used when representatives from each subgroup within the population need to be represented in the sample. Comparing respondentdriven sampling and targeted sampling.
It allows the researcher to make asymptotically unbiased estimates from snowball samples under some conditions. It is necessary to be able to sample bulk materials during shipment and during processing operations. Aug 15, 2016 presentation by giovanna merli on day 4 of social networks and health workshop at duke university. Respondent driven sampling rds is a network sampling technique typically employed for hardtoreach populations e. Examples of the test materials are bulk granular solids, slurries, sludges, grains, and solid fuels.
Sampling, measurement, distributions, and descriptive statistics basic unit of analysis, like an individual or corporation. Jun 26, 2010 the objective of this article is to compare demographic characteristics, risk behaviors, and service utilization among injection drug users idus recruited from two separate studies in san francisco in 2005, one which used targeted sampling ts and the other which used respondent driven sampling rds. Introduction to sampling error of means the message of chapter 14 seemed to be that unsatisfactory sampling plans can. You could think of your sample as a census with a great deal of nonresponse. Freedman department of statistics university of california berkeley, ca 94720 the basic idea in sampling is extrapolation from the part to the wholefrom the sample to the population. Comparision of snowball sampling and sequential sampling. Hardtoreach populations are characterized by the difficulty in sampling from them using standard probability methods. Idus were recruited using ts n 651 and rds n 534 and participated in quantitative.
A sampling frame for voters in a precinct would be the voter registration listing, for example. Respondent driven sampling rds is the method used for sampling from hardtoreach human populations. Efforts to improve the main disadvantage of snowball sampling resulted in the respondent driven sampling rds method. It is a forum for researchers who use the respondent driven sampling research methods to discuss issues and challenges around setting up a study site to recruit participants and to collect the data. Idus were recruited using ts n 651 and rds n 534 and participated in. For example, to sample x from the joint distribution px px 1x m, where there is no closed form solution for px, but a representation for the conditional distributions is available, using gibbs sampling one would perform. Each entry on the sampling frame is called a sampling unit. Stratified random sampling is simple and efficient using proc freq and proc. Formative research to optimize respondent driven sampling surveys among hardtoreach populations in hiv behavioral and biological surveillance. Respondent driven sampling rds is n approach to sampling design and inference in hardtoreach human populations. A practical guide to sampling national audit office. Similar to snowball sampling, initial seed respondents recruit additional respondents from their network of friends. All sampling frames will have some defects, despite assurances you may receive from the holder of. Sampling and estimation in hidden populations using.
The sampling frame the sampling frame is the list of ultimate sampling entities, which may be people, households, organizations, or other units of analysis. The table of the largest corporations in fortune magazine is the sampling frame for large corporations. The objective of this article is to compare demographic characteristics, risk behaviors, and service utilization among injection drug users idus recruited from two separate studies in san francisco in 2005, one which used targeted sampling ts and the other which used respondentdriven sampling rds. Respondentdriven sampling rds employs a variant of a linktracing network sampling strategy to collect data from hardtoreach populations. Sampling and estimation in hidden populations using respondent driven sampling matthew j. A r e s o u r c e g u i d e f o r s t e e r i n g c o m m i t t e e s 1 table of contents. Contacting members of the sample stratified random sampling convenience sampling quota sampling thinking critically about everyday information sample size. References respondentdriven sampling references peer driven intervention references core rds references.
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