July 7, 2017
Measure of Association
The relative risk is considered the risk among exposed subjects divided by the risk among unexposed subjects. If a risk ratio were equal to one, there is no association between exposure and disease. A risk ratio greater than none indicates that the exposure increases the incidence of the disease. However, if the risk ratio is less than one, the exposure provides protection against the disease or condition.
An odds ratio is the probability of an event occurring compared to the event not occurring in a particular group. If the odds ratio is greater than one, there is an increased likelihood of exposure among subjects who have the disease. An odds ratio less than one would indicate a decreased likelihood of exposure among diseased individuals.