study (stud´e)

Research, detailed examination, and/or analysis of an organism, object, or phenomena. [L. studium, study, inquiry]
analytic 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 epidemiological 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 epidemiological 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.
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 of all voters regardless of age, religion, gender, or geographic location are sampled in one day).synchronic s. (1) ;
diachronic s.a s. of the natural course of a 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.longitudinal s;
double blind s.a s. in which neither the experimenter nor any other assessor of the results, including patients, know which group is subject to which procedure, thus helping assure that the biases or expectations of either will not influence the results.
follow-up s. 2. study 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.ongoing epidemiologic study of a cohort of over 5,000 of the population of Framingham, MA conducted since 1949 under the auspices of the National Institutes of Health and Boston University.
longitudinal s.diachronic s
multivariate s.'sthe use of statistical techniques for the simultaneous investigations of the influence of several variables.
synchronic s. 1. cross-sectional s


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