TSA (version 0.99)

gBox: Generalized Portmanteau Tests for GARCH Models

Description

Perform a goodness-of-fit test for the GARCH model by checking whether the standardized residuals are iid based on the ACF of the absolute residuals or squared residuals.

Usage

gBox(model, lags = 1:20, x, method = c("squared", "absolute")[1], plot = TRUE)

Arguments

model

fitted model from the garch function of the tseries library

lags

a vector of maximum ACF lags to be used in the test

x

time series data to which the GARCH model is fitted

method

"squared": test is based on squared residuals; "absolute": test is based on absolute residuals

plot

logical variable, if TRUE, the p-values of the tests are plotted

Value

• lags
  lags in the input
• pvalue
  a vector of p-values of the tests
• method
  method used
• x
  x

References

"Time Series Analysis, with Applications in R" by J.D. Cryer and K.S. Chan

Examples

library(tseries)
data(CREF)
r.cref=diff(log(CREF))*100
m1=garch(x=r.cref,order=c(1,1))
summary(m1)
#gBox(m1,x=r.cref,method='squared')