Quantitative and qualitative research, and the respective research designs, are distinct from each other in many ways; and, indeed, much has been written in Research Design Review on the unique attributes of qualitative research. There are, however, commonalities across research methodologies that cannot be ignored in quality research design. These commonalities include fundamental constructs that further a principled approach to research design, such as the notion of sampling, bias, and validity.

The idea of linking, what many may consider, quantitative concepts with qualitative research may be disconcerting to some who approach qualitative research from a particular stance or paradigm orientation, or believe that quantitative jargon and ideas have no place in qualitative methods. And yet, as stated in “The Transcendence of Quality Over Paradigms in Qualitative Research,”

As important as a theoretical or philosophical orientation may be to serving as the foundation to a qualitative research effort, it need not be tied to the quality measures the researcher utilizes in the actual doing of the research. 

Meaning that a quality approach to design is critical regardless of paradigm orientation, as reinforced in “Distinguishing Qualitative Research Methods from Paradigm Orientation,”

If, philosophically, the goodness of qualitative research is of ultimate concern, and if it is agreed that qualitative research can, in fact, serve worthwhile (i.e., “good”) purposes, then logically it would serve those purposes only to the degree that it is done well, regardless of the specific objectives [or paradigm orientation] that qualitative researchers are striving to address. (Roller & Lavrakas, p. 20)

A specific example is given in “Social Contructionism & Quality in Qualitative Research Design” which states in part,

Quality considerations walk hand-in-hand with social constructionism (and many theoretical and philosophical orientations), you might even say that they need each other. A quality approach is driven by the researcher’s understanding and utilization of the socially-constructed world (e.g., use of language, the imbalance of power) while the social constructionist ultimately requires research outcomes that are useful.

In the spirit of embracing varying degrees of worldviews associated with qualitative research along with a quality approach to qualitative research design, researchers can turn their attention to fundamental constructs such as sampling. In the field of psychology, researchers such as Robinson (2014) have proposed a four-point “pan-paradigmatic” sampling framework, and Morrow (2005) emphasizes the idea that “purposeful sampling is used to produce information-rich cases, and a combination of sampling strategies may be used to achieve this purpose.” Braun and Clarke (2019) have their “own rules of thumb and make pragmatic decisions around sampling” with attention to sample size, “recognising that sample size alone is not the only factor at play. Getting different stories can require sampling more widely” (p. 11). And O’Reilly and Parker (2013) link quality to sampling, stating that the “defensibility of the quality of qualitative research, to a considerable extent, relates to sampling adequacy” (p.2).

Sampling is central to qualitative design among other social scientists — such as Adler & Adler (2012) who discuss “theoretical sampling, where researchers purposely seek to interview participants who occupy particular niches in their analysis” (p. 9), and Roller & Lavrakas (2015) who have made sampling a main feature of the Total Quality Framework Credibility component — and researchers in the health sciences. Morse (1991, 2000, 2015, 2020) is widely considered the champion of qualitative health research. Back in 1991, Morse argued for greater attention to sampling in qualitative research, emphasizing the need for closer examination of “the principles of sampling in qualitative research and to consider threats to validity and special problems that occur when making sampling decisions” (p. 129). Fast forward nearly 30 years and Morse continues her discussion of sampling strategies, stating “Sampling is…a strategy that must be approached carefully in light of many factors unique to your [qualitative] project, along with anticipating the ramifications of your sampling decision for the entire project” (2020, p. 5).

Another shared construct — bias — is the focus of Part 2 in this discussion.

Adler, P., & Adler P. (2012). In Baker, S., & Edwards, R. (Eds.), How many qualitative interviews is enough?: Expert voices and early career reflections on sampling and cases in qualitative research (pp. 8-11).  National Centre for Research Methods Review Paper. http://eprints.ncrm.ac.uk/2273/4/how_many_interviews.pdf

Braun, V., & Clarke, V. (2019). To saturate or not to saturate? Questioning data saturation as a useful concept for thematic analysis and sample-size rationales. Qualitative Research in Sport, Exercise and Health, 00(00), 1–16. https://doi.org/10.1080/2159676X.2019.1704846

Morrow, S. L. (2005). Quality and trustworthiness in qualitative research in counseling psychology. Journal of Counseling Psychology, 52(2), 250–260. https://doi.org/10.1037/0022-0167.52.2.250

Morse, J. M. (1991). Strategies for sampling. In Morse, J. M. (Ed.), Qualitative nursing research: A contemporary dialogue (pp. 127-145). SAGE Publications, Inc. https://www.doi.org/10.4135/9781483349015

Morse, J. M. (2000). Determining sample size. Qualitative Health Research, 10(1), 3–5. https://doi.org/10.1177/104973200129118183

Morse, J. M., Barrett, M., Mayan, M., Olson, K., & Spiers, J. (2002). Verification strategies for establishing reliability and validity in qualitative research. International Journal of Qualitative Methods, 1(2), 13–22.

Morse, J. M. (2015). Critical analysis of strategies for determining rigor in qualitative inquiry. Qualitative Health Research, 25(9), 1212–1222. https://doi.org/10.1017/CBO9781107415324.004

Morse, J. (2020). The changing face of qualitative inquiry. International Journal for Qualitative Methods, 19, 1–7. https://doi.org/10.1177/1609406920909938

O’Reilly, M., & Parker, N. (2013). “Unsatisfactory saturation”: A critical exploration of the notion of saturated sample sizes in qualitative research. Qualitative Research, 13(2), 190–197. https://doi.org/10.1177/1468794112446106

Robinson, O. C. (2014). Sampling in interview-based qualitative research : A theoretical and practical guide. Qualitative Research in Psychology, 11(1), 25–41.

Roller, M. R., & Lavrakas, P. J. (2015). Applied qualitative research design: A total quality framework approach. New York: Guilford Press.

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