The benefit of doing nothing

From Tim Harford:

[I]n many areas of life we demand action when inaction would serve us better.

The most obvious example is in finance, where too many retail investors trade far too often. One study, by Brad Barber and Terrance Odean, found that the more retail investors traded, the further behind the market they lagged: active traders underperformed by more than 6 percentage points (a third of total returns) while the laziest investors enjoyed the best performance.

This is because dormant investors not only save on trading costs but avoid ill-timed moves. Another study, by Ilia Dichev, noted a distinct tendency for retail investors to pile in when stocks were riding high and to sell out at low points. …

The same can be said of medicine. It is a little unfair on doctors to point out that when they go on strike, the death rate falls. Nevertheless it is true. It is also true that we often encourage doctors to act when they should not. In the US, doctors tend to be financially rewarded for hyperactivity; everywhere, pressure comes from anxious patients. Wiser doctors resist the temptation to intervene when there is little to be gained from doing so — but it would be better if the temptation was not there. …

Harford also reflects on the competition between humans and computers, covering similar territory to that in my Behavioral Scientist article Don’t Touch the Computer (even referencing the same joke).

The argument for passivity has been strengthened by the rise of computers, which are now better than us at making all sorts of decisions. We have been resisting this conclusion for 63 years, since the psychologist Paul Meehl published Clinical vs. Statistical Prediction. Meehl later dubbed it “my disturbing little book”: it was an investigation of whether the informal judgments of experts could outperform straightforward statistical predictions on matters such as whether a felon would violate parole.

The experts almost always lost, and the algorithms are a lot cleverer these days than in 1954. It is unnerving how often we are better off without humans in charge. (Cue the old joke about the ideal co-pilot: a dog whose job is to bite the pilot if he touches the controls.)

The full article is here.

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