Quantitative Concept
odds ratio
[ odz reyshoh, sheeoh ]
Subclass of:
Probability
Definitions related to odds ratio:

A measure of the odds of an event happening in one group compared to the odds of the same event happening in another group. In cancer research, odds ratios are most often used in casecontrol (backward looking) studies to find out if being exposed to a certain substance or other factor increases the risk of cancer. For example, researchers may study a group of individuals with cancer (cases) and another group without cancer (controls) to see how many people in each group were exposed to a certain substance or factor. They calculate the odds of exposure in both groups and then compare the odds. An odds ratio of one means that both groups had the same odds of exposure and, therefore, the exposure probably does not increase the risk of cancer. An odds ratio of greater than one means that the exposure may increase the risk of cancer, and an odds ratio of less than one means that the exposure may reduce the risk of cancer.NCI Dictionary of Cancer TermsU.S. National Cancer Institute, 2021

The ratio of the odds of an event occurring in one group to the odds of it occurring in another group, or to a samplebased estimate of that ratio.NCI ThesaurusU.S. National Cancer Institute, 2021

The ratio of two odds. The exposureodds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The diseaseodds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalenceodds ratio refers to an odds ratio derived crosssectionally from studies of prevalent cases.NLM Medical Subject HeadingsU.S. National Library of Medicine, 2021
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