Sampling rare populations presents many challenges. In caring for those who experience social exclusion, nurses are well placed to conduct research into these hard-to-reach populations. This article by Mary Dawood discusses some of the sampling methods used

There has long been an acceptance among academics and policy-makers that rare populations are hard to locate (Sudman and Kalton 1986, Kish 1991). Sometimes a sampling frame covering a rare population is available, an example being people with a rare disease. In most cases, however, such frames are unavailable and special sampling techniques are required.