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In epidemiology, a rate ratio, sometimes called an incidence density ratio or incidence rate ratio, is a relative difference measure used to compare the incidence rates of events occurring at any given point in time.
Incidence is usually more useful than prevalence in understanding the disease etiology: for example, if the incidence rate of a disease in a population increases, then there is a risk factor that promotes the incidence.
A case fatality ratio is a comparison between two different case fatality rates, expressed as a ratio. It is used to compare the severity of different diseases or to assess the impact of interventions. [6] Because the CFR is not an incidence rate by not measuring frequency, some authors note that a more appropriate term is case fatality ...
Calculating the infection rate is used to analyze trends for the purpose of infection and disease control. [1] An online infection rate calculator has been developed by the Centers for Disease Control and Prevention that allows the determination of the streptococcal A infection rate in a population.
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 ...
The sample odds ratio n 11 n 00 / n 10 n 01 is easy to calculate, and for moderate and large samples performs well as an estimator of the population odds ratio. When one or more of the cells in the contingency table can have a small value, the sample odds ratio can be biased and exhibit high variance .
It is computed as () /, where is the incidence in the exposed group, and is the incidence in the unexposed group. If the risk of an adverse event is increased by the exposure rather than decreased, the term relative risk increase (RRI) is used, and it is computed as ( I e − I u ) / I u {\displaystyle (I_{e}-I_{u})/I_{u}} .
In epidemiology, the attack rate is the proportion of an at-risk population that contracts the disease during a specified time interval. [1] It is used in hypothetical predictions and during actual outbreaks of disease.