Method[ edit ] A field worker was instructed to start a snowball sample of a particular trait identified as characteristic of the heroin scene. For example, there are no lists of drug users or prostitutes that a researcher could get access to, especially lists that could be considered representative of the population of drug users or Snowball research.
The key in gaining access and documenting the cooperation of subjects is trust. Strata are simply sub-groups within a population. At the zero stage, the subject selected was asked to nominate other heroin users sharing that trait the maximal number of nominees was Snowball research In this example, three samples were selected from the dataset base for analysis to meet a criterion of holding the "length" of the three samples constant.
It is possible for the surveyors to include people in the survey that they would not have known but, through the use of social network. Like other chain-referral methods, RDS assumes that those best able to access members of hidden populations are their own peers.
From the set of those nominated at each stage, a simple random selection was made of a single individual. Problems and techniques of chain referral sampling.
However, the protocol must include justification of the use of this method in the context of the study and target population. For example, studies of networks of drug users or studies tracking sex partners require extreme caution with information gathered from one subject about another.
The study team member may ask subjects to obtain permission from others prior to disclosing their contact information. Virtual snowball sampling[ edit ] Virtual snowball sampling is a variation of traditional snowball sampling and it relies on virtual networks of participants.
It brings new advantages but also disadvantages for the researcher. Snowball recruitment where the researcher obtains names and contact information from one individual for another one, particularly for research involving sensitive topics, is generally not considered appropriate by the Boise State IRB.
Snowball sampling may also be viewed as an effective sampling strategy from a perspective of research design and the choice of research methods. However, we are only interested in examining a sample of these student drug users.
If the potential subject were interested in study participation, they would be free to contact the researcher. In one subset, "foreign origin" was the trait to be saturated; in the other, it was "prostitution as occupation".
The use of virtual networks in this example of hard to reach population, increased the number of participating subjects and as a consequence, improved the representativeness of results of the study.
Alternatively, the researcher should ask other subjects to pass along flyers, emails, information sheets, etc. The information provided to enrolled subjects fliers, letters of explanation, etc.
Sample one was started with a year-old British heroin user whose referrals included a year-old Italian. Provide the IRB with a script detailing how the researcher will be obtaining the information for the snowball recruitment. If this were the case, and we would likely not know if it was or not, the sample that took part in the survey could include an over-representation of causal drug users compared with frequent drug users.
The process continues until sufficient units have been identified to meet the desired sample size. Respondent-driven sampling involves both a field sampling technique and custom estimation procedures that correct for the presence of homophily on attributes in the population.
The sensitivity of coming forward to take part in research is more acute in such research contexts. Disadvantages of snowball sampling Since snowball sampling does not select units for inclusion in the sample based on Snowball research selection, unlike probability sampling techniquesit is impossible to determine the possible sampling error and make statistical inferences from the sample to the population.
Participants or informants with whom contact has already been made can use their social networks to refer the researcher to other people who could potentially participate in or contribute to the study. The study team member may provide information to subjects and encourage them to pass it on to others who may be interested or eligible.
Graphically represented, these sampling ranged in "length" i. Also, it is imperative that the correct personnel is used to execute the actual sampling, because one missed opportunity could skew the results.
In this respect, the initial students help to identify additional units that will make up our sample. Each student is referred to as a unit [see our article, Sampling: Taking this example, imagine that we were to conduct our survey during morning lecturers at a university.Snowball sampling can happen in a number of ways, but generally it is when a group of people recommends potential participants for a study, or directly recruits them for the study.
Snowball sampling is a type of non-probability sampling technique. Non-probability sampling focuses on sampling techniques that are based on the judgement of the researcher [see our article Non-probability sampling to learn more about non-probability sampling].
In sociology and statistics research, snowball sampling (or chain sampling, chain-referral sampling, referral sampling) is a nonprobability sampling technique where existing study subjects recruit future subjects from among their acquaintances.
Thus the sample group is said to grow like a rolling snowball. Many activist investors pour in tons of research and express their opinions about the valuation of a company in their filing. Typically, this information is not available in public domain.
We have a dedicated page which tracks and monitors such information. Snowball sampling is a recruitment technique in which research participants are asked to assist researchers in identifying other potential subjects.
Back to Guidelines for Researchers Snowball sampling is a recruitment technique in which research participants are asked to assist researchers in identifying other potential subjects. The use of currently enrolled research participants to recruit additional research participants (sometimes referred to .Download