Re: [R] using garchFit() to fit ARMA+GARCH model with exogeneous variables

2009-07-01 Thread spencerg
Hello, Yuhan: If I wanted to get something sensible today, I'd do ordinary least squares using lm(y~x), the garchFit on the residuals. This will give you a reasonable answer except that the confidence intervals from "lm" will not be accurate. I'd want to do normal probability plots of

[R] using garchFit() to fit ARMA+GARCH model with exogeneous variables

2009-06-19 Thread Zhang, Yuhan
Hello - Here's what I'm trying to do. I want to fit a time series y with ARMA(1,1) + GARCH(1,1), there are also an exogeneous variable x which I wish to include, so the whole equation looks like: y_t - \phi y_{t-1} = \sigma_t \epsilon_t + \theta \sigma_{t-1} \epsilon_{t-1} + c x_t where \