When either type of study is feasible, an experiment is usually preferred over an observational study. Explain why. Also explain why it is not always possible for researchers to carry out a study in an experimental framework.

An observational study is a study in which the investigator observes the effect of the factors, diagnosis, and treatment and other type interventions.  

There are two types of observational studies:

The observational studies are open to the dispute.  

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