Predictable changes in yields and forward rates

We make two contributions to the study of interest rates, The first is to c haracterize their dynamics in a new way. We estimate forecasting relations based on one-period changes in forward rates, which are more easily compare d than earlier work on yields to the stationary theory of bond pricing, The second is to approximate these dynamics and other salient features of inte rest rates with an affine model. We show that models with 'negative" factor s come closer to accounting for the properties of interest rates, including their dynamics, than multifactor Cox-Ingersoll-Ross models. (C) 2001 Elsev ier Science S.A. All rights reserved. JEL classification. E43, G12.