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  2. Rare disease assumption - Wikipedia

    en.wikipedia.org/wiki/Rare_disease_assumption

    and = / / = While the prevalence is only 9% (9/100), the odds ratio (OR) is equal to 11.3 and the relative risk (RR) is equal to 7.2. Despite fulfilling the rare disease assumption overall, the OR and RR can hardly be considered to be approximately the same. However, the prevalence in the exposed group is 40%, which means is not sufficiently small

  3. Relative risk - Wikipedia

    en.wikipedia.org/wiki/Relative_risk

    In practice the odds ratio is commonly used for case-control studies, as the relative risk cannot be estimated. [1] In fact, the odds ratio has much more common use in statistics, since logistic regression, often associated with clinical trials, works with the log of the odds ratio, not relative risk. Because the (natural log of the) odds of a ...

  4. Number needed to harm - Wikipedia

    en.wikipedia.org/wiki/Number_needed_to_harm

    It is defined as the inverse of the absolute risk increase, and computed as / (), where is the incidence in the treated (exposed) group, and is the incidence in the control (unexposed) group. [1] Intuitively, the lower the number needed to harm, the worse the risk factor, with 1 meaning that every exposed person is harmed.

  5. Retrospective cohort study - Wikipedia

    en.wikipedia.org/wiki/Retrospective_cohort_study

    While retrospective cohort studies try to compare the risk of developing a disease to some already known exposure factors, a case-control study will try to determine the possible exposure factors after a known disease incidence. Both the relative risk and odds ratio are relevant in retrospective cohort studies, but only the odds ratio can be ...

  6. Odds ratio - Wikipedia

    en.wikipedia.org/wiki/Odds_ratio

    An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of event A taking place in the presence of B, and the odds of A in the absence of B. Due to symmetry, odds ratio reciprocally calculates the ratio of the odds of B occurring in the presence of A, and the odds of B in the absence of A.

  7. Pre- and post-test probability - Wikipedia

    en.wikipedia.org/wiki/Pre-_and_post-test_probability

    Relative risks are affected by the prevalence of the condition in the reference group (in contrast to likelihood ratios, which are not), and this issue results in that the validity of post-test probabilities become less valid with increasing difference between the prevalence in the reference group and the pre-test probability for any individual.

  8. Prospective cohort study - Wikipedia

    en.wikipedia.org/wiki/Prospective_cohort_study

    "OR" stands for "odds ratio" and "RR" stands for "relative risk". A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals ( cohorts ) who differ with respect to certain factors under study to determine how these factors affect rates of a certain outcome . [ 1 ]

  9. Hazard ratio - Wikipedia

    en.wikipedia.org/wiki/Hazard_ratio

    While the median endpoint ratio is a relative speed measure, the hazard ratio is not. [3] The relationship between treatment effect and the hazard ratio is given as . A statistically important, but practically insignificant effect can produce a large hazard ratio, e.g. a treatment increasing the number of one-year survivors in a population from ...