做ARMA-Garch,代码如下:
spec_m6 <- ugarchspec(variance.model = list(model = "sGARCH",
garchOrder = c(1, 1),
submodel = NULL,
external.regressors = NULL,
variance.targeting = FALSE),
mean.model = list(armaOrder = c(0, 0),
external.regressors = NULL),
distribution.model="sstd",
start.pars = list(),
fixed.pars = list())
garch_m6 <- ugarchfit(spec = spec_m6, data = m6, solver.control = list(trace=0))
运行结果出现警告:Warning message:
In .makefitmodel(garchmodel = "sGARCH", f = .sgarchLLH, T = T, m = m, :
rugarch-->warning: failed to invert hessian
garch_m6结果出现空值:
> garch_m6
*---------------------------------*
* GARCH Model Fit *
*---------------------------------*
Conditional Variance Dynamics
-----------------------------------
GARCH Model : sGARCH(1,1)
Mean Model : ARFIMA(0,0,0)
Distribution : sstd
Optimal Parameters
------------------------------------
Estimate Std. Error t value Pr(>|t|)
mu -0.0016 NA NA NA
omega 0.0000 NA NA NA
alpha1 0.0000 NA NA NA
beta1 0.9990 NA NA NA
skew 1.0202 NA NA NA
shape 59.9998 NA NA NA
Robust Standard Errors:
Estimate Std. Error t value Pr(>|t|)
mu -0.0016 NA NA NA
omega 0.0000 NA NA NA
alpha1 0.0000 NA NA NA
beta1 0.9990 NA NA NA
skew 1.0202 NA NA NA
shape 59.9998 NA NA NA
failed to invert hessian
LogLikelihood : 523.7385
Information Criteria
------------------------------------
Akaike -5.1774
Bayes -5.0784
Shibata -5.1791
Hannan-Quinn -5.1373
Weighted Ljung-Box Test on Standardized Residuals
------------------------------------
statistic p-value
Lag[1] 0.0004418 0.9832
Lag[2*(p+q)+(p+q)-1][2] 0.0710942 0.9404
Lag[4*(p+q)+(p+q)-1][5] 0.9238316 0.8767
d.o.f=0
H0 : No serial correlation
Weighted Ljung-Box Test on Standardized Squared Residuals
------------------------------------
statistic p-value
Lag[1] 0.6589 0.4169
Lag[2*(p+q)+(p+q)-1][5] 0.8590 0.8907
Lag[4*(p+q)+(p+q)-1][9] 1.6704 0.9405
d.o.f=2
Weighted ARCH LM Tests
------------------------------------
Statistic Shape Scale P-Value
ARCH Lag[3] 0.2434 0.500 2.000 0.6218
ARCH Lag[5] 0.2664 1.440 1.667 0.9491
ARCH Lag[7] 0.5410 2.315 1.543 0.9745
Error in t.default(grad) : 参数不是矩阵
请教大神是什么原因?怎么解决?