I distinctly recall that Robert Shiller did not recommend that people buy stocks in 2009. That made me wonder when Robert Shiller did say it was a good time to buy stocks.
By one metric — Yale professor Robert Shiller’s cyclically adjusted price-to-earnings ratio, or CAPE ratio — stocks are especially pricey. This has become the bears’ favorite valuation measure. But beware of cherry-picking any particular metric that rationalizes your position. Indeed, over the past 20 years, the CAPE measure has pegged U.S. equities as “overvalued” 85 percent of the time.
But for me, the most interesting Shiller-bashing is in the book I am reading by Duncan Watts, Everything is Obvious. He reproduces a chart created by David Pennock and Dan Reeves, using option prices to derive the probability distribution of future stock prices. The chart shows clearly that the uncertainty about future stock prices is much higher than the variation of past stock prices. That is exactly the criticism that I made of Shiller’s famous “variance bounds” estimates when he first published his work on that topic, and which he told the journal editor to reject. I still think that I was right. I should note that Watts does not make the Shiller connection in his book. However, I think that Watts gives us plenty of reason to be cautious about making statements like “Shiller called the housing bubble.”
I wish that more economists were aware of Watts.