Before revision:  Although the approach is non-parametric, it presents itself in computationally tractable and flexible restricted forms in examples we considered . Popular techniques in time series analysis such as AR, ARCH and GARCH can be seen to be special cases of our approach, but it is not clear if they are always the best or most informative choices .
After revision:  Although the approach is non-parametric, it presents itself in computationally tractable and flexible restricted form compared with the AR approach, while as a non-parametric approach, it achieves similar accuracy to the GP approach with much lower computational cost especially when the sample size is large . Popular techniques in time series analysis such as AR, ARCH and GARCH can be seen to be special cases of our approach, but it is not clear if they are always the best or most informative choices .