Mortality

Confidence in research findings and their interpretation is essential to good science. It is through attention to the internal validity of the study design that confidence can be assured in experimental studies, which attempt to show causation. These studies are common in testing theoretical predictions and in evaluating the efficacy of interventions, whether in health care, in the classroom, in organizations, or in other settings. In designing studies with strong internal validity, care is taken to ensure that the hypothesis of causation, “X causes Y,” can be clearly posited. Numerous factors can blur the interpretation of findings, referred to as threats to internal validity. One of these is mortality or the loss of subjects in a study. This entry provides an overview of the problems ...