from which we can infer that if the risk or the probability of failure is low (P\0.1), then the OR is a good approximation of the RR, and they can be used interchangeably. If the risk of the events is high, then the OR and the RR cannot be used interchangeably, since they tend to be quite different because the risk is bounded by the values of 0 and 1, whereas the odds can have values from 0 to infinity. In the comparison of RRs and ORs, we can observe the following.