Shiller points out that statistical models used by economists can't quantify the risk of a double-dip recession. Confidence indexes show gradual trends so they too are poor at picking up the dangers inherent in the increasing levels of uncertainty and the increasing vulnerability of confidence in the economy. The potential of sudden events in derailing confidence is great. He cites the 10 percent drop in the U.S. stock market on May 6, as one example. And the potential of the BP oil spill creating havoc for the Gulf economy is another such event. Shiller says his definition of a douple dip recession looks at the long term, and doesn't see the short term as a way to correctly read the economic situation. He sees a douple dip recession as a rise in unemployment to high levels, and becomes sticky after that, only nudged down insignificantly. Before unemployment can be brought down a second recession occurs, and there could be years in between. Shiller's Buy-on-Dips stock Market Confidence Index prepared since 1989 shows a steady decline in individual investor confidence since 2009....