Relative Risks

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Relative Risks

What are they?

Everitt (1998) states that Relative Risk refers to a measure of the association between exposure to a particular factor and risk of a certain outcome in which its calculation from the following formula.

                        Relative Risk = Incidence rate among exposed  ÷ incidence rate among non-exposed

Consistently, this is understood that if saying a Relative Risk of 3, this means that an exposed person is 3 times as likely to have the disease than one who is not exposed. Also it is confirmed that Relative Risk does not measure the probability that someone with the factor will develop the disease, because the disease may be rare among both the exposed and non-exposed (Everitt, 1998).

Similarly, in its website, Wikipedia (2016) states that in terms of statistics and epidemiology, relative risk (also called risk ratio)  is the ratio of the probability of an event occurring. It indicates that there are two important features of relative risks: (1) a comparison of risk between two "exposures" puts risks in context, and (2) "exposure" is ensured by having proper denominators for each group representing the exposure (Wikipedia, 2016).

Why do Relative Risks matter? 

References

Everitt, B.S. (1998). The Cambridge - Dictionary of Statistics. United Kingdom: Cambridge University Press

Useful links

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Relevant links: Risk