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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“If I were in the unenviable position of having to study my work my points of departure would be the “Naught is more real ...” and the “Ubi nihil vales ...” both already in Murphy and neither very rational.”
—Samuel Beckett (1906–1989)