Friday, February 01, 2013

Bankers and tail events

I participated in a panel last note hosted by the German American Business Association.  Overall, I had a nice time.

But before the panel, a managing director from a very large bank gave a speech, and he was trying to make some sort of point about tail risk.  The example he used is going to jail in Monopoly, an event for which the average probability is four percent.

Maybe I am being picky here, but two points.  One: four percent is not that far out on the tail.  I suppose it would be good if banks tried to avoid things that happen four percent of the time or less.  Two, and more important: random events in Monopoly come from a finite state space, so risk can be completely characterized.  We know with a great deal of certainly the probabilities of particular events happening in Monopoly.

Banks have to deal with uncertainty--random shocks that are not easily characterized by well defined distributions of outcomes.  The Monopoly metaphor is thus a bad one.

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