“…To test for the null hypothesis of a more general parametric functional form, such as a linear regression, we may apply the same approach to residuals from the parametric fit under the null model. For more general procedures, we refer to Azzalini and Bowman [7], González Manteiga and Cao [8], Härdle and Mammen [9], Fan and Li [10], Stute [11], the monograph of Hart [12], Dette and Munk [13,14], Aït-Sahalia et al [15], Fan and Huang [16], Fan et al [17], Horowitz and Spokoiny [18] and Munk [19] and the references therein. The form of the new test is motivated by recent developments in analysis of variance with large number of factor levels [20].…”