If you have taken or know about Philosophy (Critical Thinkers!)- Question 5?

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Write about Controlled studies, using examples, explain the idea and why you did or did not find it useful.

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Case-control studies are one type of epidemiological study design. They are used to identify factors that may contribute to a medical condition by comparing a group of patients who have that condition with a group of patients who do not.

Case-control studies are a relatively inexpensive and frequently-used type of epidemiological study that can be carried out by small teams or individual researchers in single facilities in a way that more structured trials often cannot be. They have pointed the way to a number of important discoveries and advances, but their retrospective, non-randomized nature limits the conclusions that can be drawn from them.

The great triumph of the case-control study was the demonstration of the link between tobacco smoking and lung cancer, by Sir Richard Doll and others after him. Doll was able to show a statistically significant association between the two in a large case control study. Opponents, usually backed by the tobacco industry, argued (correctly) for many years that this type of study cannot prove causation, but the eventual results of double-blind prospective studies confirmed the causal link which the case-control studies suggested, and it is now accepted that tobacco smoking is the cause of about 87% of all lung cancer mortality in the US.

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