| Good point. However, this example could go either way. Suppose everything you said is true, but in addition to all that, there is a set of symptoms caused by -- making this up -- endocrine disruptors in our drinking water. When pregnant women drink too much, they get some subset of symptoms from a set that overlaps 80% with the cardboard box symptoms. Now we have two different causes for different symptoms. In addition, you can get the strange case where: patient A, symptoms X, condition G patient B, symptoms X, condition H patient C, symptoms Y, condition G patient D, symptoms Y, condition H Although most of the time, condition G will have similar symptoms and condition H will have similar symptoms. That's why it is so useful to have a marker. |