Decision making and compensation

Alea references a fascinating paper by Richard Herring and Susan Wachter, Bubbles in Real Estate Markets. This makes an important point about the stability of financial return distributions:

The ability to estimate the probability of a shock – like a collapse in real estate prices – depends on two key factors. First is the frequency with which the shock occurs relative to the frequency of changes in the underlying causal structure. If the structure changes every time a shock occurs, then events do not generate useful evidence regarding probabilities.

And of course this is the case in most (all?) financial situations. The next crisis is never like the last one, in part because trading behaviour is changed by memories of the last one, in part because of product innovation and the changing structure of financial intermediation.

The important question then is

How do banks make decisions with regard to low-frequency shocks with uncertain probabilities? Specialists in cognitive psychology have found that decision-makers, even trained statisticians, tend to formulate subjective probabilities on the basis of the “availability heuristic,” the ease with which the decision-maker can imagine that the event will occur. [...]

This tendency to underestimate shock probabilities is exacerbated by the threshold heuristic (Simon(1978)). This is the rule of thumb by which busy decision-makers allocate their scarcest resource, managerial attention. When the subjective probability falls below some threshold amount, it is disregarded and treated as if it were zero.

Compensation policies make this worse. Suppose you buy insurance against a rare event that everyone else ignores. Your return suffers relative to them, and hence in most years (when the rare event does not happen), you are paid less. On the other hand, if the event does happen, the bank's total income will almost certainly fall anyway, compensation will be tight, and you will likely not be rewarded properly for being the far-sighted manager you are. On the other hand, in the bad year those who did not buy the insurance acted like nearly all their peers, and hence will probably not be punished too badly.