It is commonly found in empirical studies that nominal interest rates contain a unit root, implying that these variables have a permanent memory. One of the characteristics of a nonstationary time series is that it has no tendency to return to its mean values, meaning that the series is trending...

We consider the kernel estimation of a multivariate regression function at a point. Theoretical choices of the bandwidth are possible for attaining minimum mean squared error or for local scaling, in the sense of asymptotic distribution. However, these choices are not available in practice. We...