Introduction
The benefits of a qualitative approach to health care
research are becoming increasingly recognized by both
academics and clinicians, but misunderstandings about
the philosophical basis and the methodological approach
remain. The impression is sometimes given that
qualitative research differs from the hypotheticodeductive
model simply in terms of the way that data
is collected. The process of sampling is one of the principal
areas of confusion, a problem not helped by the
inadequate way that it is covered in the literature, where
there is little agreement on definitions and authors frequently
invent new and complex terms which cloud
simple fundamental issues. In this article I will describe
both quantitative and qualitative methods of sampling
and consider the basic differences between the two
approaches in order to explain why the sampling techniques
used are not transferable. I will consider issues
relating to sample size and selection in qualitative
research and illustrate the principles with practical
examples.