Modeling yields at the zero lower bound: are shadow rates the solution?

Recent U.S. Treasury yields have been constrained to some extent by the zero lower bound (ZLB) on nominal interest rates. In modeling these yields, we compare the performance of a standard affine Gaussian dynamic term structure model (DTSM), which ignores the ZLB, and a shadow-rate DTSM, which respects the ZLB. We find that the standard affine model is likely to exhibit declines in fit and forecast performance with very low interest rates. In contrast, the shadow-rate model mitigates ZLB problems significantly and we document superior performance for this model class in the most recent period.