Rate ratio

A rate ratio (sometimes called an incidence density ratio) in epidemiology, is a relative difference measure used to compare the incidence rates of events occurring at any given point in time. A common application for this measure in analytic epidemiologic studies is in the search for a causal association between a certain risk factor and an outcome.[1]

\text{Rate Ratio} = \frac{\text{Incidence Rate 1}}{\text{Incidence Rate 2}} [2]

Where incidence rate is the occurrence of an event over person-time, for example person-years.

\text{Incidence Rate} = \frac{\text{events}}{\text{person time}}

Note: the same time intervals must be used for both incidence rates.[2]

See also

References

  1. ↑ Bellan, Steve. "Study Design and Analysis in Epidemiology: Where does modeling fit?". Retrieved 8 April 2012.
  2. 1 2 http://www.ctspedia.org/do/view/CTSpedia/RateRatio


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