Marshall, MN. Sampling for qualitative research. Family Practice 1996; 13: 522-525.
The probability sampling techniques used for quantitative studies are rarely appropriate
when conducting qualitative research. This article considers and explains the differences
between the two approaches and describes three broad categories of naturalistic sampling:
convenience, judgement and theoretical models. The principles are illustrated with practical
examples from the author's own research.
Keyword. Qualitative sampling.