Each sub-population operating in a conflict environment can be considered difficult to reach since fear and mistrust are often pervasive [7]. Under purposeful sampling, there are several ways of selecting individuals for a qualitative study. the seed of the interview pathway was a contact we had already retained prior to the research project). Due to limited space, however, we refrain from defining terms we have deemed common in this field of study, referring only to the relevant literature. Purposeful sampling is widely used in qualitative research for the identification and selection of information-rich cases related to the phenomenon of interest. Morgan [21] has claimed that the ‘best defence’ against a lack of sample diversity is to begin the sample with seeds that are as diverse as possible. Creswell, for instance, notes that ‘the intent [of qualitative research] is not to generalise to a population, but to develop an in-depth [and contextualised] exploration of a central phenomenon’ ([42], p. 203). Initially, we conducted research via telephone only. We define key terms for this paper such as ‘snowball sampling’ or ‘sampling’, since these terms are not consistently codified in the scholarly literature. These include seven of the nine interviews conducted with dam developers, the sub-category we deemed most challenging to interview. long, in-depth foundation entries, read about the people that were pioneers for this subject, If a single request remains unanswered, the researcher may hypothesise that, for instance, the e-mail was overlooked, a hypothesis particularly likely when conducting interviews with time-pressed leaders of organisations. (3) Including personal contacts and contacts via conferences. No, Is the Subject Area "Quantitative analysis" applicable to this article? As far as we are aware, ours is the first medium-N analysis to focus on enhancing the sample diversity of a snowball sample. Snowball sampling is a commonly employed sampling method in qualitative research; however, the diversity of samples generated via this method has repeatedly been questioned. We also thank Ralf van Santen for his outstanding contributions to this work as a research assistant. Yes In this study, we performed the first quantitative, medium-N analysis of snowball sampling to … Snowball sampling was originally used by researchers to study the structure of social networks [32]. Yes https://doi.org/10.1371/journal.pone.0201710.g005. (1) Comprises interviews with those already retaining a personal or professional contact prior to the research project. I am indebted to the students who attended qualitative and feminist courses I taught during the last four years at the Hebrew University of Jerusalem and at the University of Haifa. (1) Unable to retrace for 13 identified reach-outs if initiated via referral or cold call; four reach-outs coded as ‘Other’. Please log in from an authenticated institution or log into your member profile to access the email feature. Methodological discussions have commonly addressed a variety of methods for collecting and analyzing empirical material, yet the critical grounds upon which these were reformulated have rarely been extended to embrace sampling concepts and procedures. Face-to-face interviews build trust and can help to generate further referrals. We use cookies to improve your website experience. Snowball sampling is often employed when no sampling frame can be constructed. Visualization, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands, The most frequently employed definition, suggested by Patton [5], Atkinson and Flint [6], Cohen and Arieli [7] and Bhattacherjee [8], is as a sampling method in which one interviewee gives the researcher the name of at least one more potential interviewee. Thousand Oaks, CA: Sage. Katrina Charles, Roles As a remedy for snowball sampling’s previously discussed bias towards excluding those least keen to be interviewed, multiple scholars suggest pursuing a snowball sample for multiple waves (with a new sampling wave reached once an interviewee introduces the interviewer to one or more potential interviewees) [65–68]. We wish to thank our reviewers at PLOS ONE who provided constructive thoughts on this piece of work. We acknowledge, however, that this finding may not be true for all populations. Our population of interest for our research project were stakeholders in Southeast Asia’s dam industry. Yes However, not a single interview with a dam developer was carried out in the third wave and beyond, although a fifth of our total interviews were carried out in the third or later waves. For instance, we may not have been able to trace all original reach-out attempts and our data on persistence may therefore be biased. In this study, we performed the first quantitative, medium-N analysis of snowball sampling to identify pathways to sample diversity, analysing 211 reach-outs conducted via snowball sampling, resulting in 81 interviews; these interviews were administered between April and August 2015 for a research project on anti-dam movements in Southeast Asia. No, Is the Subject Area "Qualitative studies" applicable to this article? We map this data in Fig 6, with the left side depicting our success rate in relation to the number of reach-outs (either one, two or three) and the right side depicting a deep dive on success rates achieved with two reach-outs (distinguishing between reach-out attempts to unknown potential interviewees and those to whom we were referred by other interviewees). Qualitative research employs what is generally called purposeful sampling, which is the intentional selection of individuals to better understand the central phenomenon. In order to operationalise the concept of sample diversity, we used five key methodological recommendations to inform our research. Unfortunately, we developed the idea to write this paper only during the course of our research project, and thus some of our data may be skewed. Yes Eight potential interviewees responded, but refused interview. Yes 5 Howick Place | London | SW1P 1WG. A medium-N analysis is generally based on 10–100 cases, whereas anecdotal evidence is usually based only on a handful of cases [23, 24]. Our analysis provides evidence that sample diversity can be reached even if no prior personal or professional contacts to the population of interest have been retained. Our paper has attempted to provide some insights on this effort. Patton ([5], p. 176) notes that snowball sampling ‘begins by asking well-situated people: “Who knows a lot about ____? PLOS ONE promises fair, rigorous peer review, Our descriptive analysis provides evidence to further support the argument that face-to-face interviews are redundant, with our data indicating that face-to-face interviews can lead to more sought referrals than telephone interviews (perhaps since trust may be more readily established via face-to-face conversations than over the telephone). No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0201710, http://dx.doi.org/10.1016/j.healthplace.2015.06.004, http://dx.doi.org/10.1080/10926771.2016.1157843. This access is needed to gather the widely varying viewpoints in the hydropower industry, in particular viewpoints with regards to what constitutes just resettlement [73, 74].