In epidemiology and statistics, an observational study draws inferences about the possible effect of a treatment on subjects, where the assignment of subjects into a treated group versus a control group is outside the control of the investigator. This is in contrast with experiments, such as randomized controlled trials, where each subject is randomly assigned to a treated group or a control group before the start of the treatment.
Read more about Observational Study: Reasons For Uncontrolled Experimentation, Degree of Usefulness and Reliability, Discussion
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“The traveller who has gone to Italy to study the tactile values of Giotto, or the corruption of the Papacy, may return remembering nothing but the blue sky and the men and women who live under it.”
—E.M. (Edward Morgan)