Birthday

I remember the story of "9-enders" (aged twenty-nine, thirty-nine, fifty-nine) who are much more enthusiastic to run their first marathon. In many ways, the left-digit bias reinforces our tendency to categorize continuous variables on the basis of the left-most numeric digit.

The susceptibility of our brains to fall into the trap of heuristics or hard-wired mental shortcuts is common. It can affect many of us. And we (and by we I mean runners, customers, parents, and doctors) tend to be affected without being aware of the cognitive biases.

Hey, I just found out doctors are also making clinical decisions with left-digit bias. For those of you who think high-tech physicians are awesome in calculating the risk-benefit trade-off to manage patients with acute heart attack, go and read the recent issue of the New England Journal of Medicine. Based on data of patients who were admitted to hospital with acute myocardial infarction over six years, those admitted in the 2 weeks after their 80th birthday were significantly less likely to undergo bypass surgery than those who were admitted in the 2 weeks before their 80th birthday.

The creepy reason of your being turned down for a life-saving heart surgery, in short, could have simply been the way you're categorized as being "in your 80s" rather than "in your 70s", and that, in turn, is a matter of few weeks' difference in your birthday.

Amen.