The relative risk (or risk ratio, RR) is the risk of disease in exposed divided by the risk of disease in unexposed. If the risk in the exposed is less than the risk in the unexposed, then the RR will be
The value of RR may range anywhere between zero and infinity.
An RR (or OR) of 1.0 indicates that there is no difference in risk (or odds) between the groups being compared. An RR (or OR) more than 1.0 indicates an increase in risk (or odds) among the exposed compared to the unexposed, whereas a RR (or OR)