Quantitative researchers often fail to understand the usefulness of studying small samples. This is related to the misapprehension that generalizability is the ultimate goal of all good research and is the principal reason for some otherwise sound published qualitative studies containing inappropriate sampling techniques. An appropriate sample size for a qualitative study is one that adequately answers the research question. For simple questions or very detailed studies, this might be in single figures; for complex questions large samples and a variety of sampling techniques might be necessary. In practice, the number of required subjects usually becomes obvious as the study progresses, as new categories, themes or explanations stop emerging from the data (data saturation). Clearly this requires a flexible research design and an iterative, cyclical approach to sampling, data collection, analysis and interpretation.
This contrasts with the stepwise design of quantitative studies and makes accurate prediction of
sample size difficult when submitting protocols to funding bodies