This entry from the Encyclopedia of Survey Research Methods provides a detailed overview of purposive sampling and how it can be used in evaluation. (Academic subscription needed to access).
"A form of non-probability sampling in which decisions concerning the individuals to be included in the sample are taken by the researcher, based upon a variety of criteria which may include specialist knowledge of the research issue, or capacity and willingness to participate in the research." (Oliver, 2013)
Oliver, P. (2013). Purposive sampling. In V. Jupp (Ed.), The SAGE Dictionary of Social Research Methods. Retrieved from https://methods.sagepub.com/Reference/the-sage-dictionary-of-social-research-methods/n162.xml
'Purposive sampling' is referenced in:
- Rainbow Framework :