Some people get paid to think of these things.

So my sister-in-law was telling me the other day that regular colonic irrigation is believed to lower your chances of bowel cancer. (No, I don't remember how we got onto the subject. It's a great euphemism, though, isn't it? "Colonic irrigation". Sounds like something a civil engineer might do. (Come to think of it, maybe civil engineers do do it. What do I know about the shadowy world of civil engineering?) An even better euphemism, used now by health spas and such, apparently, is "colonic hydrotherapy". My hat is off to whoever coined that.) Anyway, it got me thinking. The claim may or may not be true, but how would you go about testing it?

Well, obviously, you'd give, say, one thousand men monthly enemas for, oh, twenty years or so, and you'd leave another one thousand men alone, under strict instructions not to go getting any enemas off their own bat. But then there's the tricky bit: you have to test for placebo effect. So, somehow, you have to leave another one thousand men with the impression that they're receiving enemas without actually giving them enemas.

There are, I believe, genuine scientific statistics regarding colonic irrigation, which means that somewhere, somehow, someone has figured out how to do that.