Sampling should always be grounded by the specific aims and questions to be addressed by the study. It should also specify the characteristics of the population as well as determining the relationship between the selected population and the sampling strategy. Weiss (1994); Creswell (1998); and Mason (2002) outline several different strategies for selecting a sample of informants depending on the scope of the study, the amount of time the researcher is willing and able to spend on data collection, and the tradition of inquiry used for the project. Creswell (Creswell, 1998) also describes sixteen types of sampling and the rationale for selecting each strategy.
According to Patton (Patton, 1990), purposive sampling is considered as one of the most dominant sampling strategies in qualitative research. It seeks out rich cases which can be studied in depth, and selects subjects or sites due to specific characteristics or phenomena under study. By adopting the purposive strategy of sampling I chose to target people according to what appeared to me or from my point of view ought to have been able to provide me with valuable,
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rich and the descriptive information; in other words, according to the needs of this study. Furthermore, it is important to mention that purposive sampling is the most commonly used method of selecting participants for oral history research projects (Boschma et al., 2008).
In this case I believed that Adeni nurses as well as British nurses who worked during the studied British colonial period in SA, should be selected as 'key informants' (Johnson, 1990). It was expected that these people would prove to be a rich and valuable source of information on nursing during the period under study and it was assumed that they would be able to provide data that would shed light on this history. I was convinced that only those people who witnessed and experienced that period of time and who provided nursing services, when it is thought they were first developed and formalised, would be able to provide rich and reliable information about the past.
With respect to the nurses from SA, I could not isolate myself from the process of selecting the informants whom I felt would serve the study objectives. Although there were few concerns at the outset about finding the relevant people, indeed some of them were already known to myself, there was some doubt about whether they would be prepared to participate in this study or not, and about whether they would be able to provide information relevant to all of the research questions (Mason, 2002).
Interviewing British nurses who worked in SA during the period under investigation was a greater challenge. The following questions were of concern to myself: how could these British nurses be found? Would they be able to take part in this study? And, if they could be found, would they agree to take part? The search for these nurses was the most challenging part in the sampling phase of this study but I was fortunate to find the two British nurses and even luckier to be able to interview them. In an event related to my work with the Yemeni Development Foundation in 2001, I met with a person who worked as part of the colonial administration in SA in the 1960s as a political officer. A mention was made of this study and questions were asked about the possibility of contacting British people who worked as nurses in SA in the period when he
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served with the colonial administration. As a result, two British nurses were identified and I was provided with their email addresses.
Although sampling in qualitative research is concerned less with the actual number of participants in a given study and more with the contribution that each informant makes in producing valuable knowledge, at the beginning of the study I aimed for a certain number of interviews in the preliminary plan for the data collection process. In the original research plan, it was intended that 22 nurses from Aden would be interviewed, as we could not identify other nurses from the rest of SA, and the same number or slightly fewer interviews with British nurses would be conducted. In the end, information gathered from 12 interviews with Adeni nurses (4 females and 8 males with a mean age of 65 and two British nurses (both females with a mean age of 75) were obtained for this research (see table no 2). More interviews with British nurses would have been preferred but unfortunately, no more British nurses could be identified.
Table 2 Characteristics of the oral history interviewees Interviewee
initial
Approx. Age Gender Nationality
MM 65 Male Adeni/ South Arabian
PB 60 Male Adeni/ South Arabian
CK 65 Female Adeni/ South Arabian
AU 65 Male Adeni/ South Arabian
ML 70 Male Adeni/ South Arabian
VC 65 Male Adeni/ South Arabian
WM 70 Male Adeni/ South Arabian
PR 60 Female Adeni/ South Arabian
JD 65 Female Adeni/ South Arabian
FA 65 Male Adeni/ South Arabian
MP 65 Female Adeni/ South Arabian
AA 65 Male Adeni/ South Arabian
GG 75 Female British Nurse
FF 75 Female British Nurse
Note. Approximate ages (to the nearest 5 years) have been given in this table to help ensure anonymity.
Blanken et al., (1992) believe that the kind of snowball sampling used in this study offers certain practical advantages. One of these is where identification through social networks is more reliable than identification through formal or official lists which are no longer current. Since the key informants in this study was composed of South Arabian and British retired nurses who worked and
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trained during the British colonial period in SA from 1950-1967, most of whom have now withdrawn from the public life, using social networks proved to be effective and practical in identifying the participants.
The next section will give an account of the methods of data collection employed in this study.