In fields such as epidemiology, social sciences, psychology 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.
An observational study draws inferences about the possible effect of a treatment on subjects. This is in fields such as epidemiology. This is in fields such as social sciences. This is in fields such as psychology. This is in fields such as statistics. The assignment of subjects into a treated group versus a control group is outside the control of the investigator.