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Article Artículo

Farmer’s Folly: The Sequel
In a new working paper, UCLA’s Roger Farmer responds to last year’s investigation into his claim that declines in the stock market caused the Great Recession. Farmer apparently failed to grasp the nature of the critique. In his original paper, Farmer clai

David Rosnick / August 20, 2014

Article Artículo

Stock Returns: Between Shiller and DeLong

Robert Shiller had a piece in the Sunday NYT noting that the S&P 500 was unusually high relative to his measure of trailing earnings. He calculated a ratio above 25, far above the historic average of 15. Shiller said that in the past, each time this ratio crossed 25 the market took a plunge shortly thereafter. He concludes his piece by seeing it as a mystery that the market remains as high as it does.

Brad DeLong picks up on Shiller's analysis and points out that in most cases in the past where Shiller's ratio had exceeded 25, people who held onto their stock over the next decade would still have seen a positive real return. He notes the examples in the 1960s when investors would have seen a negative ten-year return, even though Shiller's ratio was below the critical 25 level. He therefore concludes there is no issue.

I would argue there is an issue, although not quite as much as Shiller suggests. To get at the problem, we have to recognize that stock returns, at least over a long period, are not just random numbers. Both Shiller and DeLong treat this as a question of guessing whether an egg will turn into a lizard or chicken based on the distribution of past hatchings that we have witnessed.

That would be a reasonable strategy if that is the only information we have. But if we saw that one of the eggs was laid by a hen, then we may want to up our probability estimate that it will hatch into a chicken.

In the case of stock returns we can generate projections based on projections of GDP growth, profit growth, and future price to earnings ratios. For example, we may note that the ratio of stock prices to after-tax corporate profits for the economy as a whole was 22.3 at the end of 2013. (This takes the value of stock from the Financial Accounts of the United States, Table L.213, lines 2 plus 4 for market valuation. After-tax corporate profits are from the National Income and Product Accounts, Table 1.10, Line 17).

This means that earnings are roughly 4.5 percent of the share price. If companies pay out 70 percent of their earnings as dividends or share buybacks (roughly the average), this translates into a 3.1 percent real return in the current year.

Dean Baker / August 18, 2014