Case Control Studies

Case control studies are studies in which patients who already have a certain condition are compared with people who do not.

 For example: a study on which lung cancer patients are asked how much they smoked in the past and the answers are compared with a sample of the general population would be a case control study.

 Case control studies are less reliable than either randomized controlled trials or cohort studies. Just because there is a statistical relationship between two conditions does not mean that one condition actually caused the other. For instance, lung cancer rates are higher for people without a college education (who tend to smoke more), but that does not mean that someone can reduce his or her cancer risk just by getting a college education.

The main advantages of case control studies are:

• They can be done quickly. By asking patients about their past history, researchers can quickly discover effects that otherwise would take many years to show themselves.
• Researchers don't need special methods, control groups, etc. They just take the people who show up at their institution with a particular condition and ask them a few questions.