What type of sampling strategy is used when a researcher recruits friends of interviewees to participate?

The use of network sampling is characterized by recruiting participants through referrals from existing subjects. In this scenario, when a researcher invites friends of interviewees, they are leveraging existing social connections to expand their sample size. This method is particularly effective when the target population is hard to reach or not easily identified through traditional sampling methods.

Network sampling helps researchers tap into social networks, allowing them to gather diverse perspectives within a community. This can lead to a more comprehensive understanding of the research subject since participants often share similar experiences or characteristics within their social circles. This approach can also help in recruiting participants who are more likely to be willing to engage, as they come recommended by someone they trust.

Other methods, such as random sampling, systematic sampling, and stratified sampling, do not involve utilizing participants' social networks to recruit additional subjects and thus do not apply in this context.