GARCH-BEKK

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Kaloyan Bozhidarov
Kaloyan Bozhidarov 2011-6-17
[EDIT: 20110617 09:06 CDT - reformat - WDR]
Hi,
I want to evaluate the volatility spill over between bonds, cds and equity using company data.
However, I have a problem with my GARCH BEKK model. I used UCSD toolbox, and followed the following steps for the estimation of the model. Built a ARMA model and obtained the residuals, then demeaned the residuals and run the GARCH BEKK model. Everything is fine so far, but the problem is that I get insignificant results for the coefficients that reflect the volatility spillover.
This is my code:
%ARMA fiting
[parameters, errors, LLF , SEregression, stderrors, robustSE, scores, likelihoods]=armaxfilter(rstock,1,1,1)
%Ljung Box test for serial correlation
[H,pValue,Qstat,CriticalValue] = lbqtest(errors,[5 ,10],0.01)
resstock=errors
resstock=resstock-mean(resstock)
%ARMA fiting
[parameters, errors, LLF , SEregression, stderrors, robustSE, scores, likelihoods]=armaxfilter(rbond,1,1,1)
%Ljung Box test for serial correlation
[H,pValue,Qstat,CriticalValue] = lbqtest(errors,[5 ,10],0.01)
resbond=errors
resbond=resbond-mean(resbond)
%ARMA fiting
[parameters, errors, LLF , SEregression, stderrors, robustSE, scores, likelihoods]=armaxfilter(rcds,1,1,1)
%Ljung Box test for serial correlation
[H,pValue,Qstat,CriticalValue] = lbqtest(errors,[5 ,10],0.01)
rescds=errors
rescds=rescds-mean(rescds)
x=[resbond rescds resstock]
%GARCH BEKK estimation
[parameters, loglikelihood,likelihoods, stdresid, stderrors, A, B, scores] = full_bekk_mvgarch(x,1,1)
%%%%%Test for adequacy
stdresid2=stdresid.^2 %square of the std resid
%Ljunk Box Test
[h,pValue,stat,cValue] = lbqtest(stdresid2,20)
qqplot(stdresid2)
%%%%Extracting std errors from A
st=diag(A,0)
st=sqrt(st)
Could anybody help me?

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回答（3 个）

Junjun
Junjun 2012-7-27
Why does this coefficient ought to be significant?
  1 个评论
Javier
Javier 2012-9-24
Normally you get the error of the coefficient estimated with the sqrt(diag(hessian(something))). Don not what is A.

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Javier
Javier 2012-12-3
编辑：Javier 2012-12-10
Hello Kaloyan
I just start checking UCSD GARCH toolbox. Once you get the H value for the lbqtest of the square residuals equal to 0, it means that the model is ok (UNIVARIATE). To get the Significance of the parameters I use this formula:
parameters/sqrt(diag(A)).
Now you have to test significance in the multivariate sense. There is no function in Matlab or MFE toolbox for that purpose. In this book you can find a multivariate test (New introduction to multiple time series analysis (Luetkepohl 2005) Hope this helps
Javier
Javier 2012-12-4
Hello Kaloyan
I just talk with professor Sheppard. There is a new toolbox MFE with the same functionalities. Erase UCSD Toolbox and prove with the new one.
Best regards
Mauricio

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