<p>There is an economic literature on sample design that, although fairly well advanced for quantitative studies (such as randomised controlled trials), has yet to extend to the analysis of qualitative research designs. This paper proposes a simple economic model of qualitative research designs in which “saturation” is a consideration. It shows how concepts from the qualitative literature, along with some concepts economists have applied to quantitative research, including in the so-called “Value of Information (VoI)” literature, may be extended to consider the topic of saturation through an economic lens. While there is considerable debate in the current qualitative literature over whether the concept of saturation is necessary, or useful, the results may be of interest to researchers who need, or want, to incorporate considerations regarding saturation in their research designs.</p>