It can be a frustrating, and rather futile, experience to be an economist. Financial markets do not always behave as if there is a connection between economic fundamentals and stock prices, a subject I touched on in the October 2012 letter. In fact, if you believe the findings of a recent Vanguard study, rainfall statistics provide more value than either trend GDP growth or trend earnings growth in terms of their ability to predict future stock market returns (chart 1).