Lean Manufacturing

Sampling method

According to extant theory there are two core sampling categories, namely probability and non-probability sampling, which entail several types of sampling techniques (Remenyi, 1998; Bernard, 2000; Ghauri & Gronhaug, 2002; Reynolds, Simintiras & Diamantopoulos, 2003; Saunders, Lewis & Thornhill, 2009). In probability sampling, such as simple random or stratified sampling, each subject has a known, non-zero chance of being selected in the sample, thus it allows statistical inferences. This category is usually applied by quantitative based research strategies. In contrast, with non-probability samples, such as convenience, judgmental and purposive sampling, the probability of each unit being selected from the total population is unknown (ibid.). In this case, the researcher chooses the individuals to be

193 included in the sample based on subjective arguments. This technique is usually adopted in case study research (Saunders et al., 2007).

Also, sampling processes in qualitative studies are not prescribed so rigidly as in quantitative research (Coyne, 1997). However, this flexibility in sampling could be confusing for various scholars and mistakes could be made (ibid.). Sampling decisions are mainly determined by the appropriateness of developing relevant and in-depth information (Flick, 2006; Li, 2014). The current study adopted purposeful sampling strategy during the process of selecting the key informants which belongs to the non-probability category.

Purposeful sampling is defined as the choice of archetypical cases where phenomena are most likely to serve the theoretical purpose and research questions of the research study (Silverman, 2000; Poulis, Poulis & Plakoyiannaki, 2013). Similarly, Patton (1990) which is often cited as an authority on purposeful sampling (Suri, 2011), defined purposeful sampling as the process of choosing information-rich cases from the perspective of a specific study's research aim. Selecting cases according to the purposeful sampling criteria, means selecting cases from which in-depth insights and understandings can be captured, rather than empirical generalizations (Dubois & Araujo, 2007). In other words, for qualitative research like the case study research design, the purposeful sampling logic for selecting of key informants involves using replication logic in combination with choice of information-rich cases and is mainly based on the conceptual framework developed from prior wisdom (Perry, 1988). In doing so, purposeful sampling also helps in increasing the robustness and applicability of the findings (Yin, 1994; Miles & Huberman, 1994; Wagner, 2006).

194 This study's application illustrates how purposeful sampling could integrate with additional methodological tools to provide a sampling framework that is characterized as context-sensitive. In other words, the principles of purposeful sampling permeated the research project's sampling logic, pointing the need for a theory-driven choice of key informants along with a consideration of contextual idiosyncrasies (Bryman, 2004; Poulis et al., 2013).

In particular, the study selected the key informants on a purposive sampling logic with an attempt to encompass all the selection criteria set in the previous section. Also, the adoption of purposeful sampling enabled the researcher to select key informants that are characterized as information-rich cases that could provide insightful and rich data for the phenomenon under investigation in this study.

Sample size of key informants

As regards to the number of interviews, a research study must also rationalize and provide the number of key informants to interview when conducting a case study research design.

To start with, some other authors provide precise numbers for sample size when conducting a qualitative research. For instance, de Ruyter and Scholl (1998) state that a qualitative research study rarely reaches 60 respondents and smaller samples of between 15 and 40 respondents are the most common. In doing so, Marshall et al. (2013) examined 83 Information Systems (IS) top performing qualitative articles (defined as the most highly respected), in top IS journals and they found no evidence that studies with more than 30 interviews had significantly more impact. Thus, they suggested that for grounded theory qualitative studies should include between 20 to 30 interviews. With regards to case study research, Creswell (2007) similarly recommends no more than 4 to 5 cases with 3 to 5 interviewees per case (overall 12 - 25 respondents).

195 In contrast to these, Patton (2002) suggests that in qualitative inquiry there are no rules of sample size of key informants to include in a qualitative research study (Marshall et al., 2013). Moreover, according to Creswell (as cited in Pollard, 2008), a small sample size is acceptable in qualitative research as the quality of the data are more important than the size of the sample. Adding to this, qualitative research is mainly concerned with understanding phenomena and concepts rather than measuring them (Bock & Sergeant, 2002; Gordon &

Langmaid, 1988). Also, according to Daymon & Holloway, (2010), in most cases qualitative sampling does not incorporate large numbers of key informants, because this could prohibit in-depth insight and richness of data (Daymon & Holloway, 2010). In order to verify their statement and cross-check whether small sample sizes are applied by researchers that conduct qualitative case studies, the researcher searched such papers from top business journals and found ample of evidence which verifies this argument. For example: Smith, et al. (2009), published a qualitative case study at the Journal of Operations Management and they did only 11 interviews, whereas, Murphy and Davey's (2002) paper published in Human Resource Management Journal entailed 16 interviews.

Also, Doldor et al. (2013) conducted a qualitative case study which was published in British Journal of Management and they did only 14 interviews. Finally, Beadle (2013) published a case study in Journal of Business Ethics at the same year and he conducted 6 interviews only.

According to the abovementioned rationale, the aim of the thesis was an in-depth understanding of the subject under exploration and not a statistically valid large sample.

Thus, the adequacy of the sample size was verified by the rich contextual data that were retrieved by the semi-depth semi-structured interviews and not by the number of interviews

196 conducted. Also, the researcher followed the guidelines by Eisenghard (1989), for which her paper on 'Building theories from case study research' is the most widely accepted and established paper in case study research and published in the top Journal of all Business disciplines (Academy of Management Review). According to the author, researchers should stop adding cases when theoretical saturation is reached. Theoretical saturation is the point at which “subsequent data incidents that are examined provide no new information” (ibid.).

An example of study that applies these guidelines is the paper of Kreiner et al. (2009) published at the Academy of Management Journal. Thus, after 20 interviews with key informants the researcher stopped conducting other interviews, because, the examined key informants provided no new information/ data any more, thus indicating the achieved saturation of the findings, which also came as another confirmation of the adequacy of the sample size.

Sampling Procedures and summary of respondents' profiles

Based on the purposive sampling logic and the aforementioned selection criteria, a pool of possible candidates was identified via the researcher's professional network. Potential participants were approached through an invitation letter in the form of an informed consent (see Appendix G). This invitation letter informed them about the purpose of the research study, confidentiality issues and the preservation of their anonymity, the identity of the researcher, how the information gathered will be used, what is the nature of their participation, the main subjects to be covered, and how much time approximately they must allocate if they chose to participate. A brief description of the key informant criteria of this research is shown in table 5.3 below, while table 5.4 illustrates the profile of the actual participants of this study, as well as their socio-demographic characteristics.

197

Acculturation issues 10 years abroad as the maximum acceptable

198 research was able to attain substantial variation within the sample. Respondents were divided evenly between men (11) and women (9) and covered a consistent spectrum of ages, from 23 to 39 years, with a mean age of 32, thus conforming to the age indications mentioned earlier in the chapter. In addition, the respondents were customers within the banking industry of Cyprus for several years, with an average number of 13 years.

Regarding the education level of respondents, all were educated at tertiary education level and employed in a variety of professions. Finally, 12 of the respondents were married and from those 7 have children.