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Research and Measurement Methodology 40 d. Snowball Sampling Snowball sampling is a method for identifying and sampling the cases in a network.For example, if we running a survey on street children/or carrying out a survey of risk behaviors amongst intravenous drug users, there will be no list with the homeless children and it will be difficult to locate this population in one place e.g. a school/hospital.Instead of the researcher choosing participants and directly contacting them, people volunteer themselves (e.g. by responding to a public online survey).

Research and Measurement Methodology 40
d. Snowball Sampling
Snowball sampling is a method for identifying and sampling the cases in a
network. This method is used when the population cannot be located in a specific
place and therefore, it is different to access this population. In this method, the
investigator asks each subject to give him access to his colleagues from the same
population, so the sample increases in size like a rolling snowball.
For example, if we running a survey on street children/or carrying out a survey of
risk behaviors amongst intravenous drug users, there will be no list with the
homeless children and it will be difficult to locate this population in one place e.g. a
school/hospital. Here, the investigators will deliver the survey to one child then, ask
him to take them to his colleagues or deliver the surveys to them.
e. Voluntary response sampling
Similar to a convenience sample, a voluntary response sample is mainly based
on ease of access. Instead of the researcher choosing participants and directly
contacting them, people volunteer themselves (e.g. by responding to a public online
survey).