Research that involves the application of the behavioral and social sciences to the study of the actions or reactions of persons or animals in response to external or internal stimuli. (from American Heritage Dictionary, 4th ed)
The integration of epidemiologic, sociological, economic, and other analytic sciences in the study of health services. Health services research is usually concerned with relationships between need, demand, supply, use, and outcome of health services. The aim of the research is evaluation, particularly in terms of structure, process, output, and outcome. (From Last, Dictionary of Epidemiology, 2d ed)