The Design
Naturalistic -- refers to studying real-world situations as they unfold naturally; nonmanipulative and noncontrolling; the researcher is open to whatever emerges [i.e., there is a lack of predetermined constraints on findings].
Emergent -- acceptance of adapting inquiry as understanding deepens and/or situations change; the researcher avoids rigid designs that eliminate responding to opportunities to pursue new paths of discovery as they emerge.
Purposeful -- cases for study [e.g., people, organizations, communities, cultures, events, critical incidences] are selected because they are “information rich” and illuminative. That is, they offer useful manifestations of the phenomenon of interest; sampling is aimed at insight about the phenomenon, not empirical generalization derived from a sample and applied to a population.