I am reading (courtesy of Ezra Klein) William Easterly's wildly enthusiastic review of Nobelist economist Daniel Kahneman’s Thinking, Fast and Slow, about the workings of our unconscious and conscious thinking processes. I encounter a quick-summed conclusion that looks a little dicey to me:
Even worse, we don’t know what we don’t know. In one experiment, chief financial officers of corporations were asked to forecast the return on the Standard & Poor’s index over the following year, giving one number they were 90 per cent sure was too high and another they were 90 per cent sure was too low. The true number was outside their intervals 67 per cent of the time.Wait, I think...what year? 2008, perhaps? To assess the 90% confidence level, wouldn't you want, say, 10 years? And do I need to buy the book to check this out?
Nah... Google experiment cfos forcast S&P next year 90 percent. And lo:
