Observational studies Observational studies are ones where researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to change who is or isn't exposed to it. Archival is the observation of previous data that has been collected and analyzed often for another purpose. Observational studies are aimed at delivering statistics and important data that can be used by researchers to come up with important theories and ideas. The process governing the exposures arguably resembles random assignment.Thus, natural experiments are observational studies and are not controlled in the . In clinical trails, the researcher would divide the participants into two more groups and control the way they behave, while noting the changes or results. The problem lies in actually identifying a cause and effect because there are so many variables (1). Compare the "natural experiment" to an observational study 2. Lab experiments are done in extremely controlled environment where every little thing can be monitored and altered if needs be. Research Guides: Epidemiology: Observational Studies PDF Comparing SARS-CoV-2 natural immunity to vaccine-induced ... - medRxiv 1) Observational Study: A study in which the researcher merely observes what is happening or what has happened in the past and tries to draw conclusion based on these observations. Usually, there is some pre-designed method for recording observations so the database can be mined later. On the other hand, an experiment refers to a research method where there are two specific groups or else variables that are used to test a hypothesis. A cohort is a group that has something in common; in epidemiology this is frequently risk of a developing a disease of interest. natural experiment vs observational study