Relative Risk Increase (RRI)

Relative Risk Increase

 

The proportional increase in frequency of harmful outcomes between experimental and control participants. It is calculated by dividing the frequency or risk of harmful outcome in the experimental group minus the frequency or risk of harmful outcome in the control group by the frequency or risk of harmful outcome in the control group. If an adverse outcome occurs in 15% of the exposed and 10% of the unexposed the relative risk increase is 50%. Typically used with a harmful exposure.

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