This paper generalizes the locally optimal linear rank test based on copula from Shirahata (1974) resp. Guillén and Isabel (1998) and Genest et al. (2006) to p dimensions and introduces a new X2-type test for global independence (Nelsen test). The test is compared to similar nonparametric tests...

We examine a kernel regression smoother for time series that takes account of the error correlation structure as proposed by Xiao et al. (2008). We show that this method continues to improve estimation in the case where the regressor is a unit root or near unit root process.