[1] They require fewer resources but provide less evidence for causal inference than a randomized controlled trial.
However, because the difference between the cases and the controls will be smaller, this results in a lower power to detect an exposure effect.
If the outcome of interest is uncommon, however, the size of prospective investigation required to estimate relative risk is often too large to be feasible.
In several situations, they have greater statistical power than cohort studies, which must often wait for a 'sufficient' number of disease events to accrue.
[citation needed] Case–control studies are observational in nature and thus do not provide the same level of evidence as randomized controlled trials.
The most important drawback in case–control studies relates to the difficulty of obtaining reliable information about an individual's exposure status over time.
[citation needed] One of the most significant triumphs of the case–control study was the demonstration of the link between tobacco smoking and lung cancer, by Richard Doll and Bradford Hill.
Case–control studies were initially analyzed by testing whether or not there were significant differences between the proportion of exposed subjects among cases and controls.
The validity of the odds ratio depends highly on the nature of the disease studied, on the sampling methodology and on the type of follow-up.
[19] Tetlock and Gardner claimed that the contributions of medical science to increasing human longevity and public health were negligible, and too often negative, until Scottish physician Archie Cochrane was able to convince the medical establishment to adopt randomized control trials after World War II.