Intéressant article de Gavyn Davis sur la difficulté pour les économistes de prédire l’apparition de ruptures, comme une crise financière par exemple. Extrait :
« Although it is often entertaining to poke fun at economists, they are not the only professional group which finds it difficult to make accurate predictions about disruptive future events. In fact, this seems to be a problem which is alarmingly common among many of the social sciences, if not of the natural sciences. The definitive work on this question was published in 2005 by Philip Tetlock, a philosophy professor at Berkeley. His book (“Expert Political Judgment”, which is well summarised here in The New Yorker) won many prizes when it first appeared, but it still seems to be very little known among economic policy makers. Which is a great pity.
Tetlock systematically collected a vast number of individual forecasts about political and economic events, made by recognised experts over a period of more than 20 years. He showed that these forecasts were not very much better than making predictions by chance, and also that experts performed only slightly better than the average person who was casually informed about the subject in hand. Depressingly, he found that there were remarkably small gains to greater expertise when it came to forecasting accuracy.
This result, which applied to politics and international relations as well as economics, emphasises how hard it is to forecast disruptive or discontinuous events – in fact, events which are not indicated by relatively simple extrapolations of recent past trends. The credit crisis was certainly not one of those “forecastable” events. If we ask why economists failed to predict the credit crisis, we should also ask why political scientists failed to predict the recent Egyptian rebellion, or indeed a terrorist event like 9/11. Or why seismologists cannot predict earthquakes. »
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