This paper proposes bootstrap assisted specification tests for the autoregressive fractionally integrated moving average model based on the Bartlett <italic>T</italic>-process with estimated parameters whose limiting distribution under the null depends on the estimated model and the estimation method employed....

Asymptotically efficient estimates for the multiple equations nonlinear regression model are obtained in the presence of heteroskedasticity of unknown form. The proposed estimator is a generalized least squares based on nonparametric nearest neighbor estimates of the conditional variance...