With this post, we'll conclude our series on sampling techniques. Today we’re going to talk about the snowball sampling method.
Snowball sampling is a nonrandom sampling method in which the individuals selected to be studied recruit new participants from among their circle of acquaintances. The word “snowball” comes from just that idea: in the same way that a snowball becomes bigger and bigger as it rolls down a hill, this method enables the sample size to grow as the individuals selected to participate invite people they know to join.
Snowball sampling is often used to access low-incidence populations and individuals who are difficult for researchers to connect with. For studies that hope to study a very specific group, such as stamp collectors, obtaining a sample through collectors’ networks of friends and acquaintances can prove much more effective than selecting individuals in a strictly random fashion, since, in the latter case, the overwhelming majority of candidates will be dismissed. In theory, it is highly likely that a stamp collector will know other stamp collectors, which makes this an effective method of sampling a group that a researcher would otherwise have difficulty accessing.