OR (within risk takers) = (1000/1000)/(900/2100) = 2.33
OR (overall, unadjusted) = (1000/1000)/(900/7100) = 7.89
As in Table 2, it is assumed that there is no use of A or B among the “unadventurous”. Here, however, the use of A and B is assumed to be correlated among the “risk takers”. It is demonstrated that the unadjusted odds ratio is substantially higher than the OR in the “risk takers”.