The 'snowball' metaphor relates to the fact that the study expands, using additional participants gathered from the original sample subjects and provides further elements for study of the subject. This progressive development of the study is the actual snowball effect. This form of sampling is typically used in specific studies of things like drug use, gaming, or other common activities to the study group.
Examples of Snowball Sampling:
|A snowball sample is created for World of Warcraft. A few users at a certain relevant levels of WoW recommend other users as sample material for the study, which is designed to study usage patterns for hardcore gamers. The choice of confirmed sources of information also helps validate the study data.|