Reconciling the Return Predictability Evidence In-Sample Forecasts, Out-of-Sample Forecasts, and Parameter Instability

55 Pages Posted: 13 Jan 2012

See all articles by Martin Lettau

Martin Lettau

University of California - Haas School of Business; Centre for Economic Policy Research (CEPR); National Bureau of Economic Research (NBER)

Stijn Van Nieuwerburgh

Columbia University Graduate School of Business; National Bureau of Economic Research (NBER); Centre for Economic Policy Research (CEPR); New York University Stern School of Business, Department of Finance

Multiple version iconThere are 4 versions of this paper

Date Written: January 2012

Abstract

Evidence of stock return predictability by financial ratios is still controversial, as documented by inconsistent results for in-sample and out-of-sample regressions and by substantial parameter instability. This paper shows that these seemingly incompatible results can be reconciled if the assumption of a fixed steady-state mean of the economy is relaxed. We find strong empirical evidence in support of shifts in the steady-state and propose simple methods to adjust financial ratios for such shifts. The forecasting relationships of adjusted price ratios and future returns is statistically significant, stable over time, and present in out-of-sample tests. We also show that shifts in the steady-state are responsible for the parameter instability and poor out-of sample performance of unadjusted price ratios that are found in the data. Our conclusions hold for a variety of financial ratios and are robust to changes in the econometric technique used to estimate shifts in the steady-state.

Suggested Citation

Lettau, Martin and Van Nieuwerburgh, Stijn, Reconciling the Return Predictability Evidence In-Sample Forecasts, Out-of-Sample Forecasts, and Parameter Instability (January 2012). NYU Working Paper No. 2451/31432. Available at SSRN: https://ssrn.com/abstract=1983090

Martin Lettau

University of California - Haas School of Business ( email )

Haas School of Business
545 Student Services Building
Berkeley, CA 94720
United States
5106436349 (Phone)

HOME PAGE: http://faculty.haas.berkeley.edu/lettau/

Centre for Economic Policy Research (CEPR)

London
United Kingdom

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Stijn Van Nieuwerburgh (Contact Author)

Columbia University Graduate School of Business ( email )

3022 Broadway
Uris Hall 809
New York, NY New York 10027
United States

HOME PAGE: http://https://www0.gsb.columbia.edu/faculty/svannieuwerburgh/

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Centre for Economic Policy Research (CEPR)

London
United Kingdom

New York University Stern School of Business, Department of Finance ( email )

44 West 4th Street
Suite 9-190
New York, NY 10012-1126
United States

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