“…For an arbitrary function , let ϕ denotes its Fourier transform, that is, and for a real random variable Z , we denote by ϕ Z its characteristic function. To estimate the regression function m , Fan and Truong () proposed the following kernel estimator: where First, notice that in the error‐free case (i.e., when X is observed) and when we dispose a sample ( X 1 , Y 1 ),…,( X n , Y n ) distributed as the pair ( X , Y ), the estimator of proposed by Jones et al () is given by …”