This recent post, on the health effects of drinking a glass of wine a day, reminds me of a story:
Several years ago my cardiologist in the U.S. recommended that I drink a glass of red wine a day for health reasons. I’m not a big drinker—probably I average something less than 100 glasses of wine a year—but when I remember, I’ll drink a glass or two with dinner when it’s available. I don’t love the taste of wine, but some of it is OK, and I already preferred the taste of the red to the white, so at least that worked out.
Anyway, awhile after receiving this recommendation, I spent a year in France, and I had to see a doctor and get a physical exam there as a condition of my work permit. The doctor asked me a bunch of questions (and spoke slowly enough that I could converse), including how much did I drink? I said I drink a glass of red wine a day on the recommendation of my cardiologist (ummm, I probably said “the doctor for my heart” or something like that). The French doctor replied that I should stop drinking as it’s bad for my foie.
I was taken aback. The U.S. doctor (not originally from this country, but still) said I should drink more; the French doctor said I should drink less. Some of this could be attributed to specialization: the cardiologist focuses on the heart, while the general practitioner thinks in terms of total risk. But, still, it was a surprise: I’d think it would be the French doctor who’d be more positive about the effects of a daily drink of wine.
OK, this is N=2 so we can learn almost nothing from this story: it could just be that this French doctor hates alcohol for other reasons, for example. Nonetheless, I’ll spin a statistical tale that goes like this:
Both doctors are being Bayesian. The U.S. doctor, upon hearing from me that I drank occasionally but rarely, inferred that: (a) I don’t drink a lot, and (b) I could drink a bit more without worry that I’d start to drink heavily. In contrast, all the French doctor heard was that I drink a glass of wine daily. From this she could’ve inferred that I might be a heavy drinker already and just not admitting it, or that if I was given any encouragement, I might drink to excess. In addition to all that, alcohol consumption is higher in France than the U.S., so the French doctor is probably used to telling her patients to drink less.
What did I actually do, you might ask? I split the difference. I continued to drink red wine but didn’t make such an effort to drink it every day.