Figure 1
From: Applying results from clinical trials: tranexamic acid in trauma patients
Two hypothetical trials: the risk ratio is the generalizable measure of the effect of treatment. In both trials, the biological effect of the treatment is the same, corresponding to a one third reduction in the risk of death. The relative risk is the same in both trials and reflects the biological effect of the treatment. However, the risk difference is not the same. The relative risk is a generalizable measure of the biological effect of a treatment, whereas the risk difference is not generalizable.