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Just to be clear, snowball sampling is a group of techniques. Chaining is one approach.
Snowballing can be a type of convenience sample, it is most often a form of purposive sampling, and it might, if done correctly, approximate a random sample. Snowball samples are not pure random samples.
Thanks for your question Koketso Mphahlele. Many thanks for the explainations Nissim Cohen and Steven Venette
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