For nonsmokers and are lazy, the probability of being lactose intolerant is 13%. For nonsmokers and are hard-working, the probability of being lactose intolerant is 96%. For smokers and are lazy, the probability of being lactose intolerant is 3%. For smokers and are hard-working, the probability of being lactose intolerant is 69%. For nonsmokers, the probability of being hard-working is 64%. For smokers, the probability of being hard-working is 49%.
If we disregard the mediation effect through effort, would smoking positively affect lactose intolerance?
This example is no.