U.S. Soybean Yields: Estimation and Forecasting with Nonsymmetric Disturbances

Abstract

National average soybean yields are skewed with a relatively high chance of low yields. Maximum likelihood estimates support this hypothesis. Revised forecasts which account for skewed yields are positioned higher than forecasts based on the illusion of a symmetric distribution. Also, yield instability has been increasing steadily; the standard deviation of the soybean yield distribution is twenty‐five percent higher in the late 1980s than it was in the early 1970s.