Snowball Recruitment - active and passive

Snowball recruitment is a method of sampling where researchers recruit potential participants from among their acquaintances or through other participants. While snowball recruitment may be advantageous in some research designs, it is important to assess the following:

  • Whether the potential for bias from the snowball method would impact on the research outcomes.
  • Is there the potential for any real or perceived coercion to be applied in the recruitment process?
  • The possibility for a breach of privacy for a nominated individual.

Snowball recruitment – in either the passive or active form – is acceptable as long there is no real or perceived coercion to take part in the research by either the researchers or other participants, and as long as there is no breach of Commonwealth, State or Territory privacy legislation involved in accessing contact details for potential participants.

Passive snowball recruitment is generally the preferred approach, where participants may be asked to discuss the research with friends/contacts who they think may be suitable or interested in volunteering to be participants. The potential participants can then be given the contact details of the research team so that they may independently volunteer to participate.

However, there may be disciplinary and field contexts in which the researchers may prefer a form of active snowballing.

Active snowball recruitment, where participants volunteer the contact details of potential participants to the researcher should be justified by the researcher in the ethics application. If proposing an active form of snowballing, the researchers need to be able to demonstrate that due ethical consideration has been given to the issues relating to privacy, and to the capacity of potential participants to give free, informed consent.

In this circumstance, it is important that the potential participant is informed from where their contact details were obtained, and the informed consent process ensures that the approach is free of real or perceived coercion. If there is a potential for a breach of privacy, an argument must be made in the application for ethics approval, weighing the potential benefits of the research proceeding in such a manner against the harm of that breach.