Absolute risk is best defined in conjunction with relative risk. For this example, we can define risk as the likelihood of an adverse consequence in two behavioral medicine interventions, Treatment A and Treatment B. Imagine that the risk is 1 in 10 for Treatment A and 2 in 10 for Treatment B. In this case, a relative risk statement can be made, saying that the probability of the event occurring following Treatment B is twice the probability of the event occurring following Treatment A. However, the same relative risk statement can be made for probabilities of 1 in 1,000,000 and 2 in 1,000,000. However, the absolute risks are vastly different: 1 and 2 in 10; and 1 and 2 in a million.
Imagine that an intervention with beneficial therapeutic properties increased your risk of an adverse consequence (an event) from 1 in 10 to 2 in 10. It is possible that some individuals may consider that the risk is too great, and that they are not prepared to take this risk. Now...