Rate ratio

A rate ratio (sometimes called an incidence density ratio or incidence rate 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]

References

Bellan, Steve. "Study Design and Analysis in Epidemiology: Where does modeling fit?". Retrieved 8 April 2012.
"Rate Ratio". www.ctspedia.org.

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[1] Bellan, Steve. "Study Design and Analysis in Epidemiology: Where does modeling fit?". Retrieved 8 April 2012.

[ctspedia-2] "Rate Ratio". www.ctspedia.org.

Rate ratio

See also

References