The Issue of Generalizability

External Validity, Generalizability, and Knowledge Utilization

“…Random selection and random assignment of participants, although not always feasible, increase the generalizability of findings to the target population, and possibly to other populations. Threats such as interactions of treatment and setting, or of treatment and history, can be addressed methodologically by introducing multisite aspects to the study, by addressing timing of studies such that history varies, or through replication (Fahs, Morgan, & Kalman, 2003; Hayes, 1998). Researchers could acknowledge historical events occurring during the course of the study, and, if possible, address these threats through data collection in a variety of circumstances.…”

“…To generalize theory to other populations or to add to existing knowledge of the discipline, research concepts, hypotheses, operational definitions and measures must be based within the theoretical framework (Chinn & Kramer, 1999). Evaluation research on the application of theory to and across populations should be conducted and reported, especially for policy development (Rich, 1991; Whittemore & Grey, 2002) and for international application (Hayes, 1998). Research findings might generalize to and across other populations and settings in the form of theory, and thus add to the knowledge of the discipline, but this generalization is possible only if the research operations are strongly based in theory (Bear, 1990; Shadish et al, 2002).…”

“…Winer (1999) and Lynch (1999) indicated the need for further studies to demonstrate external validity of the findings of a study, suggesting that the original research might have limited external validity. Replication studies and evaluation studies are key to assessing the proposed external validity of the original research findings, especially if the results have been or are expected to be incorporated into health or social policy (Fahs et al, 2003; Hayes, 1998; Lynch, 1999). Replication studies can reduce the threats to external validity, thus improving generalizability.…”

“…The topic of external validity is largely absent in nursing literature. A search of CINAHL between 1982 and 2002 revealed no nursing articles and only three editorials dealing with external validity or generalizability as the main focus (Hayes, 1998; Hegyvary, 2002; Schmitt, 1999). Researchers need specific strategies to address external validity as a critical element in research design and in utilization of research‐generated knowledge in clinical practice and policy development.…”

Generalizability: beyond plausibility and handwaving

“…1987; Cox 1992; Altman & Bland 1998; Dans et al . 1998; Hayes 1998; Rothman & Greenland 1998b). Most authors, however, offer no specific answers and some merely state their beliefs.…”