Identify and explain one disadvantage of using snowball sampling to investigate the effects of streaming on students' experience of school.

Snowball sampling is a non-probability sampling technique where existing study subjects recruit future subjects from among their acquaintances. It is often used when the target population is hard to access (e.g., criminal gangs). The main disadvantage is that it is highly unlikely to produce a representative sample. The sample is self-selecting and biased towards the social networks of the initial contacts. In a school context, this would likely result in a sample of students who are all friends with each other, probably from the same stream and with similar views, thus failing to capture the diversity of experiences across different streams.