Incorporating Uncertainty into USDA Commodity Price Forecasts
研究了美国农业部农产品价格预测的改进方法，通过密度预测格式替代旧有的区间或单点估计，利用历史数据和期权隐含波动率生成更准确、反映市场不确定性的预测。
From 1977 through April 2019, USDA published monthly season‐average price (SAP) forecasts for key agricultural commodities in the form of intervals meant to indicate forecasters' uncertainty but without attaching a confidence level. In May 2019, USDA eliminated the intervals and began publishing a single point estimate—a value that has a very low probability of being realized. We demonstrate how a density forecasting format can improve the usefulness of USDA price forecasts and explain how such a methodology can be implemented. We simulate 21 years of out‐of‐sample density‐based SAP forecasts using historical data, with forward‐looking, backward‐looking, and composite methods, and we evaluate them based on commonly‐accepted criteria. Each of these approaches would offer USDA the ability to portray richer and more accurate price forecasts than its old intervals or its current single point estimates. Backward‐looking methods require little data and provide significant improvements. For commodities with active derivatives markets, option‐implied volatilities (IVs) can be used to generate forward‐looking and composite models that reflect (and adjust dynamically to) market sentiment about uncertainty—a feature that is not possible using backward‐looking data alone. At certain forecast steps, a composite method that combines forward‐ and backward‐looking information provides useful information regarding farm‐level prices beyond that contained in IVs.