To obtain the t student of each rolling window with EGARCH model

Hello Alexios

I have advanced in my research and now I will want to get the student t from each past rolling window (500 days for each window) from 2001 to 2016 and not the student t from each forcasting rolling window.
My question has evolved and is following your response of September 12th.

For the EGARCH model, I used Package ?Rugarch? :

spec2b<-ugarchspec(variance.model=list(model="eGARCH",garchOrder=c(1,1),external.regressors=L1),          mean.model=list(armaOrder=c(0,0),archm=TRUE,archpow=1,external.regressors=L2), distribution.model = "std")
fit2b<-ugarchfit(spec=spec2b,solver="hybrid", data=RENT)
show(fit2b)
roll1=ugarchroll(spec2b,data = RENT,n.start = NULL,window.size=500,solver = "solnp" )
coeff(roll1)

coef(roll1) allows me to get the student t from the 500 forecasting windows but not the student t from past windows (500 days per windows) from 2001 to 2016.

Could you orient me to a solution ? I am looking for a solution for several days.

Thank you very much

Sandrine BOULERNE
University of Tours
www.iae.univ-tours.fr


----- Mail original -----
De: "alexios" <alexios at 4dscape.com>
?: "Sandrine Boulerne" <sandrine.boulerne at univ-tours.fr>
Cc: r-sig-finance at r-project.org
Envoy?: Mardi 12 Septembre 2017 06:27:33
Objet: Re: To obtain the t student of each rolling window with EGARCH model

Have you tried 'coef(roll1)'?

I think the documentation is reasonably clear (?ugarchroll).
It returns an object of class 'uGARCHroll' (which is clickable in the
documentation and will take you to the class help page).
In the class help page you will see that one of the methods on the class
is:

"coef
signature(object = "uGARCHroll"): Extracts the list of coefficients for
each estimated window in the rolling backtest."

Therefore, coef(roll1) will return the list of coefficient matrices
per roll window, from which you can extract the shape parameter of the
standardized Student distribution.

Similarly, please read the documentation for ugarchdistribution.


-Alexios

On 9/11/2017 9:03 AM, Sandrine Boulerne wrote:

Good Morning,

I investigate the day-of ?the-week of 11 indices in 11 countries using
EGARCH model and rolling sample method with one sample interval case of
500 days. The main purpose of the empirical analysis is to determine
whether there exist calendar effects or not by observing whether the /t/
values exceed the quantile of the standard normal distribution z = 1.96
for confidence level of 5%. I want to use the same method as Zhang, Lai,
Lin (2017), ?the day-of-the-week effects of stocks markets in different
countries?, Finance Research Letters 20.

For the EGARCH model, I used Package ?Rugarch?, and everything is good:

spec2b<-ugarchspec(variance.model=list(model="eGARCH",garchOrder=c(1,1),
external.regressors=L1),
mean.model=list(armaOrder=c(0,0),archm=TRUE,archpow=1,external.regressors=L2),

distribution.model = "std")

fit2b<-ugarchfit(spec=spec2b,solver="hybrid", data=RENT)

show(fit2b)

But for the rolling sample method, with EGARCH(1,1), I thought using
  ??ugarchroll? or ?ugarchdistribution*?, **?to calculate the student /t/
for each rolling window*, *but **I do not get student /t/* :

dist <- ugarchdistribution(fit2b, n.sim = 500, n.start = 1, m.sim = 100,
solver = "solnp")

show(dist)

or

roll1=ugarchroll(spec1b,data = RENT,n.start = NULL,window.size =
500,solver = "solnp" )

show(roll1)

Could you orient me to a solution ?

Thank you very much



Sandrine BOULERNE
Ma?tre de Conf?rences - Habilitation ? Diriger des Recherches (HDR)
IAE de Tours - Facult? de Droit, ?conomie et Sciences Sociales
50 av. Jean Portalis, BP 0607, 37206 TOURS Cedex 3
T?l?phone : 02 47 36 10 47
www.iae.univ-tours.fr