[R-SIG-Finance] MSE from GARCH forecast

[ahmed_shamiri at yahoo.com]

Hi every one
 
I would like to compute MSE on out of sample forecast from GARCH model. I used rgrach package to obtain the estimated variance (sigma2.hat). then I run an out of sample forecast as
forc = ugarchforecast(fit.garch, n.ahead=100)
this will give me 100 observation of sigma.forc( the forecasted values)
to obtain the MSE theoretically is 
MSE = 1/h+1 { sum(sigma2.hat – sigma2.forc)^2}
What confuse me is that the length of sigma2.hat actually is equal to my data length (2000 observation), while the length of sigma2.forc is only 100.
 
Can someone kindly enlighten me about this. 
 
Sincerely,
 Shamiri