Design Types and Purposes

Yin suggests that case-study designs vary according to two distinct dimensions.

One dimension accounts for the number of “cases” being studied: the

presence of either single- or multiple-case designs. A second dimension allows

for case studies to be either “holistic” (studying the entire unit of analysis

as a single global entity) or “embedded” (allowing multiple units of analysis

to be studied for the purpose of understanding their interworkings).

According to Yin, this classification system leaves the researcher with a

choice among four different design types: single-case (holistic) design, single-

case (embedded) design, multiple-case (holistic) design, and multiplecase

(embedded) design. Choosing among these designs involves the kinds

of research questions that the researcher is attempting to answer.

Case-study methods are initiated for a variety of reasons, one of which is

to serve as a vehicle for exploratory research. As a new research area begins

to develop, the initial uncharted territory is sometimes best studied (particularly

when the research questions are ill-defined) using a case-study method

to determine which direction should be pursued first. This method has therefore

been commonly misperceived as being able to contribute only in a limited

exploratory capacity; however, the case study can, and should, be used

not only to help focus initial research questions but also to describe and explain

behaviors. As Yin makes clear, both “how” questions and “why” questions

can be answered by this approach.