In grounded theory studies, theoretical sampling is driven by the emerging theory: researchers continuously collect, code, and analyze data to decide which groups or individuals to sample next in order to develop categories and their properties. In phenomenologic studies, sampling is purposive and guided by the principle that all participants must have experienced the phenomenon and can articulate that lived experience, while also seeking diversity among those participants. Theoretical sampling is therefore dynamic and contingent on ongoing analysis, whereas phenomenologic sampling is typically fixed in its focus on people who share a particular experience.

Grounded theory theoretical sampling differs from phenomenologic sampling in its purpose and procedure. Theoretical sampling is a distinctive grounded theory strategy in which sampling decisions are not made before the study begins. Instead, the researcher jointly collects, codes, and analyzes data and then chooses the next people, groups, or situations based on what is needed to develop the emerging theory. For example, a researcher may start with a few cases and later turn to new groups to refine categories, seek negative or disconfirming cases, and continue until theoretical saturation is reached. By contrast, sampling in phenomenologic studies follows a single guiding principle: all participants must have personally experienced the phenomenon under study and must be able to describe what it was like. Phenomenologic researchers typically use very small samples, often 10 or fewer, and they may deliberately seek demographic or other variation among participants who share the experience. The key difference is that phenomenologic sampling is based on the experience criterion and diversity within experienced persons, while grounded theory theoretical sampling is dynamically directed by the state of the evolving theory and the need to saturate conceptual categories.

Key points

Theoretical sampling in grounded theory is guided by the emerging theory and occurs concurrently with data collection and analysis.
In theoretical sampling, decisions about which groups or individuals to sample next are made only as needed for theoretical relevance, not before the study.
Phenomenologic sampling requires that all participants have lived the experience of the phenomenon and can articulate that experience.
Phenomenologic samples are usually very small, often 10 or fewer, and may include diverse individuals who share the same experience.
Grounded theory samples are often about 20 to 30 people and are adjusted serially and contingently as conceptualizations evolve.
Theoretical sampling continues until theoretical saturation is achieved and may include searching for confirming and disconfirming cases.

How does theoretical sampling in grounded theory studies differ from sampling in phenomenologic studies?