[R-SIG-Finance] External Regressors in GARCH Equation when using Twinkle

Neil Patrick Lawton ne||@|@wton2 @end|ng |rom m@||@dcu@|e
Thu Sep 12 01:54:53 CEST 2019

Hello all,

I am having trouble with the inclusion of external regressors in the GARCH
equation, when using the twinkle package kindly provided by Alexios
I believe I am including the data correctly to starspec. An xts object,
which is pre-lagged and has the same index as the data included within
starfit optimization.

Below, I have included an example of my code, with some generated data.


xts1 <- xts(x=rnorm(100), order.by=Sys.Date()-1:100)

xts2 <- xts(x=rnorm(100), order.by=index(xts1))

spec = starspec(mean.model = list(states = 2,

                                   include.intercept = c(1,1),

                                   arOrder = c(1,1),

                                   maOrder = c(2, 2),


                                   statevar = 'y',

                                   ylags = 3,

                                  statear = TRUE),


                                   model="sGARCH",submodel = NULL,



                                  variance.targeting = FALSE),

                                  distribution.model = "norm")

ctrl=list(maxit=1000, alpha=0.2, beta=0.1, gamma=0.7, reltol=1e-12,


mod = starfit(spec, data = xts2,

              solver.control = ctrl,

               solver = "msoptim")

I get the following error when trying to run, which only occurs when the
'vreg' argument is included in the variance model:

Error in matrix(vexdata, ncol = modelinc[39]) :

  object 'vexdata' not found

I get errors with other solvers also, whether I am including the
solver.control list or not.

In the rugarch package, the external regressors should be included as a
matrix, not an xts object. However, when I include data as a matrix here, I
get: starspec-->error: vreg must be an xts object.

Is there a solution or work around to this problem?

Kind regards,



Séanadh Ríomhphoist/_

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