How To Justify Sample Size In Qualitative Research

Sample Size: What is an appropriate sample for qualitative studies?

Interviews are a normally used data collection method in qualitative studies, where the goal is to empathise or explore a phenomenon. They're an extremely effective way to gather rich, descriptive data about people's experiences in a program or exhibition, which is ane reason we use them often in our work at RK&A. Figuring out sample size for interviews can sometimes experience trickier than for quantitative methods, similar questionnaires because there aren't tools like sample size calculators to apply. However, there are several important questions to consider that can assistance guide your decision-making (and while you exercise so, retrieve that a cornerstone of qualitative research is that it requires a high tolerance for ambivalence and instinct!):

How much does your population vary? The more homogenous the population, the smaller the sample size. For example, is your population all teachers? Do they all teach the same grade level? If so, y'all can use a smaller sample size, since the population and related phenomenon are narrow. By and large speaking, if a population is very homogeneous and the phenomenon narrow, aim for a sample size of around 10. If the population is varied or the phenomenon is circuitous, aim for around xl to fifty. And if you desire to compare populations, aim for 25 to 30 per segment. In any case, a sample of more 100 is generally excessive.
What is the scope of the question or phenomenon yous are exploring? The more narrow the question beingness explored or phenomena being studied, the smaller your sample size tin can be. Are yous looking at ane programme, or just i attribute of a program? Or, are you comparing programs or looking at many different aspects of a program?
At what point will you accomplish back-up? This is central for determining sample size for any qualitative information collection method. You lot want to sample only to the signal of saturation—that is, stop sampling when no new information emerges. Another way to think about this is that you stop collecting data when you keep hearing the same things once more and again. To be clear, I'm talking about large trends here—while each interview will have its own nuance and the minor details might vary from interview to interview, you lot tin finish when the larger trends start to repeat themselves and no new trends ascend.

The question of "how many" for qualitative studies might always feel a chip frustrating, since (every bit illustrated by the questions above) the answer volition always be "information technology depends." But think, as the give-and-take "qualitative" suggests, it'south less about verbal numbers and more almost understanding the quality of responses, including the breadth, depth, and range of responses. Each report will vary, but as long as you consider the questions to a higher place the adjacent time you are deciding on sample size for qualitative methods, you can be confident you're approaching the study in a systematic and rigorous way.