Only negative cases where the outcome was possible belong in an analysis

Evidence

Possibility Principle: Choose as negative cases those where the outcome of interest is possible. Obviously, much depends on how we interpret the key concept of “possible,” which is used to draw the boundary between the negative and irrelevant observations. We propose two rules for implementing this principle in qualitative analysis: a Rule of Inclusion and a Rule of Exclusion. — Gary Goertz, Social Science Concepts, 1155

Categorization

• DEFINE: Introduces the Possibility Principle, the chapter’s central conceptual framework.