The ratio of the odds of a condition or disease in an exposed population to the odds of the same condition or disease in a nonexposed population.

The odds of an outcome on one variable, given a certain status on another variable(s). This ratio expresses the increase in risk of a given outcome if the variable is present.

The odds ratio (OR) could have been termed “relative odds” to indicate the similarity to relative risk. It is the ratio of the odds of an event under one condition (or group) to the odds under another condition. Relative risk is a similar ratio using probabilities rather than odds. OR is a comparative quantity of the odds of an event occurring in one group compared to the odds of the event occurring in the other group. It is interesting to note that the OR also can be computed from the ratio of the RR between groups of the event occurring to the RR of the event not occurring. ORs are preferred to RR if the probability of an event is small, in case-controlled studies, and retrospective examinations when prospective studies would be impractical (e.g., the OR of getting lung cancer comparing long-time cigarette smokers to persons who never smoked cigarettes).

Ratio of the odds of disease among the exposed compared with the odds of disease among the unexposed. For rare diseases, including some cancers, the odds ratio is an estimate of the relative risk.

a statistical measure of the likelihood of developing a disease or condition if exposed to a certain factor or pathogen.

is the odds of an experimental patient suffering an event relative to the odds of a control patient..

Ratio of two odds numbers. EX: If the odds of preterm delivery are .428 in a normal population and .630 among women who have periodontal disease, the odds ratio is 1.472 (.630 / .428). Odds ratios are often used to express risk factors. An odds ratio greater than 1 represents increased risk. [See also odds

The odds of an event, understood best by those who enjoy wagers, is the number of times it occurred () divided by the number of times it didn’t ( or a/b. This contrasts with the probability of an event which is the number of times it occurred divided by the number of times it could have occurred, or a/a+b. The odds ratio is the ratio of the odds of an event in one group divided by the odds in another group. When the event rate or absolute risk in the control group is small (less than 20% or so), then the odds ratio is very close to the relative risk.

A technique for estimating relative risk from case-control studies. See Relative odds ratio.

a measure of association that can give us an idea of the direction and magnitude of the relative odds of choosing one place of treatment over another for different levels of some explanatory variable

an approximation of relative risk derived from case-control studies

The usual way of expressing the result of a case-control epidemiological study, often nearly the same as the relative risk or risk ratio. An odds ratio of 1 means there is no association between exposure and disease. Odds ratio greater than 1 mean the exposure is associated with the disease.

The ratio of the odds of disease for the experimental group relative to the odds of disease in the control group.

(Syn: cross-product ratio, relative odds): a measure of the degree of association; for example, the odds of exposure among the cases compared with the odds of exposure among the controls. ( Harm) To Calculation

a measure of treatment effect that compares the probability of a type of outcome in the treatment group with the outcome of a control group, i.e., [Pt ¸ (1 - Pt)] ¸ [Pc ¸ (1 - Pc)]. For instance, if the results of a trial were that the probability of death in a control group was 25% and the probability of death in a treatment group was 10%, the odds ratio of survival would be [0.10 ¸ (1.0 - 0.10)] ¸ [(0.25 ¸ (1.0 - 0.25)] = 0.33. (See also absolute risk reduction, number needed to treat, and relative risk.)

The ratio of the odds with experimental treatment and that of control

A measure of association which quantifies the relationship between an exposure and health outcome from a comparative study; also known as the cross-product ratio.

describes the odds of an experimental patient suffering an adverse event relative to a control patient. See also Study Designs.

Odds ratio (OR) is the odds of having a target disorder (a particular disease or event) in the experimental group relative to the odds of having the target disorder (a particular disease or event) in the control group. It's a way of comparing whether the probability of a certain event is the same for two groups (in a retrospective study). An odds ratio of 1 implies that the event is equally likely in both groups. An odds ratio greater than one implies that the event is more likely in the first group. An odds ratio less than one implies that the event is less likely in the first group.

The odds ratio is a relative measure of risk, showing how much more at risk a person exposed to a given factor will be to developing the outcome disease/condition being studied, compared to someone who has not been exposed. An odds ratio greater than one suggests that the exposure places a person at greater risk of developing the outcome being studied.

Statistics: An odds ratio is the odds of an event happening in an experimental group expressed as a proportion of the odds of the event happening in a control group. Where events are rare, odds ratio becomes analogous to relative risk. See: Relative Risk

One measure of a treatment's clinical effectiveness. If it is equal to 1, then the effects of the treatment are no different from those of the control treatment. If the OR is greater (or less) than 1, then the effects of the treatment are more (or less) than those of the control treatment. Note that the effects being measure may be adverse (eg death, disability) or desirable (eg stopping smoking).

Ratio of probability of an event in one group to probability of the event in a compared group.

describes the odds of a patient in the experimental group having an event divided by the odds of a patient in the control group having the event or the odds that a patient was exposed to a given risk factor divided by the odds that a control patient was exposed to the risk factor.

The ratio of the odds of having the target disorder in the experimental group relative to the odds in favour of having the target disorder in the control group (in cohort studies or systematic reviews) or the odds in favour of being exposed in subjects with the target disorder divided by the odds in favour of being exposed in control subjects (without the target disorder). Do you want to see how this is calculated

A measure of association between two characteristics; useful when a case-control study is used 33

A comparison of the presence of a risk factor for disease in a sample of diseased subjects and non diseased controls. The number of people with disease who were exposed to a risk factor (Ie) over those with disease who were not exposed (Io) divided by those without disease who were exposed (Ne) over those without who were not exposed (No). Thus OR=(Ie/Io)/(Ne/No)= Ie No / Io Ne. This measure should be used for case control studies where we retrospectively look at risks in those with and without disease. Also known as exposure odds ratio

An estimate of the relative risk calculated in case-control studies. It is the odds that a patient was exposed to a given risk factor divided by the odds that a control was exposed to the risk factor. Disease No Disease Risk factor present a b Risk factor absent c d Odds ratio = a x d/b x c

describes the odds of an experimental patient suffering an adverse event relative to a control patient. See also section on Odds Ratios.

A relative measure of the difference in exposure between the diseased (cases) and not diseased (controls) individuals in a case-control study. The OR is interpreted similarly to the relative risk.

The odds ratio is a measure of effect size particularly important in Bayesian statistics and logistic regression.