study

Research, detailed examination, and/or analysis of an organism, object, or phenomena. [L. studium, s., inquiry]

- analytic s. in epidemiology, a s. designed to examine associations, commonly putative or hypothesized causal relationships; usually concerned with identifying or measuring the effects of risk factors or with the health effects of specific exposures.

- blind s. a s. in which the experimenter is unaware of which group is subject to which procedure.

- case control s. an epidemiologic method that begins by identifying persons with the disease or condition of interest (the cases) and compares their past history of exposure to identified or suspected risk factors with the past history of similar exposures among persons who resemble the cases but do not have the disease or condition of interest (the controls).

- cohort s. a s. using epidemiologic methods, such as a clinical trial, in which a cohort with a particular attribute ( e.g., smokers, recipients of a drug) is followed prospectively and compared for some outcome ( e.g., disease, cure) with another cohort not possessing the attribute. SYN: follow-up s. (1).

- cross-over s. a s. in which the subject is switched from the experimental to the control procedure (or vice versa).

- cross-sectional s. a s. in which groups of individuals of different types are composed into one large sample and studied at only a single point in time ( e.g., a survey in which all members of a given population, regardless of age, religion, gender, or geographic location, are sampled for a given characteristic or finding in one day). SYN: synchronic s..

- diachronic s. SYN: longitudinal s..

- double blind s. a s. in which neither the patients, the experimenter, nor any other assessor of the results, knows which individuals are subject to which procedure, thus helping to ensure that the biases or expectations of either will not influence the results.

- ecologic s. epidemiologic s. in which the units of analysis are populations or groups of people rather than individuals.

- flow-volume loop studies diagnostic methods in which inspiratory and expiratory flow-volume curves are used to determine the location of an obstruction in the tracheobronchial tree.

- follow-up s. 1. SYN: cohort s.. 2. s. in which persons exposed to risk or given a designated preventive or therapeutic regimen are observed over a period or at intervals to determine the outcome of the exposure or regimen.

- Framingham Heart S. the first major U.S. s. of the epidemiology of cardiovascular disease, begun in Framingham, Massachusetts, in 1948 under the auspices of the National Heart Institute (now the National Heart, Lung, and Blood Institute) and still in operation. Initially the Framingham researchers enrolled over 5000 people between the ages of 30 and 60 to s. the evolution of heart disease and identify risk factors for heart attack. In 1971, offspring of the original s. participants began to be enrolled for a second generation of observations.The Framingham s. has had a major impact on the modern understanding of cardiovascular disease and on the prevention and treatment not only of heart attack but also of stroke. During the 1960s, cigarette smoking, elevated cholesterol, hypertension, obesity, and lack of exercise were all statistically confirmed to be risk factors for heart attack. In the succeeding years, the s. has provided invaluable information on triglycerides, LDL cholesterol, mitral valve prolapse, heart failure, atrial fibrillation, stroke, diabetes, cardiovascular risk factors in ethnic minorities, and the role of estrogen in preventing heart attack in postmenopausal women. After a half-century, the s. continues to provide new clues to the causation and prevention of heart disease and other cardiovascular disorders.

- longitudinal s. a s. of the natural course of life or disorder in which a cohort of subjects is serially observed over a period of time and no assumptions need be made about the stability of the system. SYN: diachronic s..

- multivariate studies the use of statistical techniques for the simultaneous investigations of the influence of several variables.

- synchronic s. SYN: cross-sectional s..

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(studґe) 1. an examination or procedure. 2. a research project; see also examination, test, and trial.