crystalcai 发表于 2012-5-29 13:09 
那是可以用igarch吗?
我们没教过figarch,老师没要求。。。
我用的是R软件。。
系数加起来是1.06,说明收益率的方差序列是非平稳的
收益率可能服从IGARCH 过程,IGARCH models are unit-root GARCH
##########
library(rgarch)
data=read.table("sp5.txt")
variance.model=list(model="iGARCH",garchOrder=c(1,1))
mean.model=list(armaOrder=c(0,0),include.mean=T,garchInMean=F)
spec=ugarchspec(variance.model=variance.model,mean.mode=mean.model,distribution.model="norm")
fit=ugarchfit(data=data,spec=spec)
fit
Model : iGARCH (1,1)
Exogenous Regressors in variance equation: none
Include Mean : TRUE
AR(FI)MA Model : (0,0,0)
Garch-in-Mean : FALSE
Exogenous Regressors in mean equation: none
Conditional Distribution: norm
Optimal Parameters
--------------------------
Estimate Std. Error t value Pr(>|t|)
mu 0.007406 0.001526 4.8542 0.000001
omega 0.000051 0.000017 2.9219 0.003480
alpha1 0.142854 0.021433 6.6653 0.000000
beta1 0.857146 NA NA NA
Robust Standard Errors:
Estimate Std. Error t value Pr(>|t|)
mu 0.007406 0.001589 4.6619 0.000003
omega 0.000051 0.000019 2.6907 0.007131
alpha1 0.142854 0.024974 5.7201 0.000000
beta1 0.857146 NA NA NA
LogLikelihood : 1268.238