The data examined included identifiable groups such as Kuwaiti Bidouns and Palestinians, individuals for whom voluntary return has proved impossible and refused asylum-seekers who have not departed from the UK territory. It was considered likely that such groups would include a proportionately much higher number of stateless persons than contained in other classifications. It was hoped that combining the analysis of direct and indirect data with evidence obtained from the qualitative and legal research would allow conclusions to be drawn about the number and profile of the population under study. 1.3.2 Qualitative methodology The second element of the methodology was to encourage the participation of stateless and “unreturnable” persons in the research in order to provide a better understanding of their situation and profile. At the outset, the researchers aimed to interview 40 stateless and “unreturnable” persons, to hear their stories and, with their permission, obtain and review their immigration case file. A number of challenges were identified. The fact that stateless and “unreturnable’ persons are part of a hidden population poses a methodological challenge17 in that no source of information detailing the geographical distribution and social-demographic characteristics of stateless people in the UK currently exists. Therefore, due to the absence of a reliable sampling frame from which to draw a probability sample, it was necessary to adopt more unorthodox alternative strategies for locating participants. Purposive sampling was therefore used, a method not based on random chance but on pre-determined judgments. Participants are identified because they have particular features or characteristics that will enable detailed exploration of the research objectives. Two forms of sampling were combined. Snowball sampling Snowball sampling is used when respondents from the sample population are particularly hard to locate and is the classic method for finding hidden populations.18 The snowball technique relies on referrals from initial contacts to supply additional contacts with good knowledge of the target population. The technique produces a wide range of contacts and information by a system of “chain referral” and serves to provide access to those persons who would otherwise be difficult to contact.19 This technique relies on trust being built up between the researcher, intermediary (or “gatekeeper”) and the interviewee, with the gatekeeper acting as an advocate for the project. As a result, gatekeepers help to facilitate the research through their organisations, encouraging the participation of potential respondents who might not have been willing to be interviewed without the recommendation of a gatekeeper. This approach assumes that the selection of subjects stops once it has reached its saturation point, which can be identified when the same points are brought up repeatedly during interviews or alternatively when quotas have been met. 17 Beata, D., Estimating the size of the homeless population in Budapest, Hungary, Research Support Scheme: Virtus, 2000. 18 Sawyer, C., and Blitz, B., K. (eds.), Statelessness in the European Union: Displaced, undocumented, unwanted, Cambridge University Press, 2011. 19 Atkinson, R., and Flint, J., Accessing Hidden and Hard to Reach Populations: Snowball Research Strategies, Social Research Update, 33, 2001. in the United Kingdom 17