gamlss.util (version 4.2-7)

garmaFit: A function to fit a GARMA model

Description

This function is for fitting a GARMA model, see Benjamin et al. (2003).

Usage

garmaFit(formula = formula(data), order = c(0, 0), 
         weights = NULL, data = sys.parent(), 
         family = NO(), alpha = 0.1, 
         phi.start = NULL, theta.start = NULL, 
         tail = max(order), control = list())

Value

It returns a fitted garma model.

Details

The model is described in Benjamin et al. (2003). The implementation here is more general that it allows all the gamlss.family distributions to be fitted thather than only for the exponential family which was described in the original formulation.

References

Benjamin M. A., Rigby R. A. and Stasinopoulos D.M. (2003) Generalised Autoregressive Moving Average Models. J. Am. Statist. Ass., 98, 214-223.

Rigby, R. A. and Stasinopoulos D. M. (2005). Generalized additive models for location, scale and shape,(with discussion), Appl. Statist., 54, part 3, pp 507-554.

Stasinopoulos D. M., Rigby R.A. and Akantziliotou C. (2006) Instructions on how to use the GAMLSS package in R. Accompanying documentation in the current GAMLSS help files, (see also http://www.gamlss.com/).

Stasinopoulos D. M. Rigby R.A. (2007) Generalized additive models for location scale and shape (GAMLSS) in R. Journal of Statistical Software, Vol. 23, Issue 7, Dec 2007, http://www.jstatsoft.org/v23/i07.

See Also

gamlss.family, gamlss

Examples

data(polio)
ti <- as.numeric(time(polio))
mo <- as.factor(cycle(polio))
x1 <- 0:167    #Index used in Tutz p197
x2 <- cos(2*pi*x1/12)
x3 <- sin(2*pi*x1/12)
x4 <- cos(2*pi*x1/6)
x5 <- sin(2*pi*x1/6)
# all the data here 
da <-data.frame(polio,x1,x2,x3,x4,x5, ti, mo)
rm(ti,mo,x1,x2,x3,x4,x5)

#-------------------------------------------------------------------
# with linear trend 
m00 <- garmaFit(polio~x1+x2+x3+x4+x5, data=da, order=c(0,0), family=NBI, tail=3) # 
m10 <- garmaFit(polio~x1+x2+x3+x4+x5, data=da, order=c(1,0), family=NBI, tail=3) # 

m01 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(0,1), data=da, family=NBI, tail=3)
m20 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(2,0), data=da, family=NBI, tail=3)
m11 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(1,1), data=da, family=NBI, tail=3)
m02 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(0,2), data=da, family=NBI, tail=3)
m30 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(3,0), data=da, family=NBI, tail=3)
m21 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(2,1), data=da, family=NBI, tail=3)
m12 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(1,2), data=da, family=NBI, tail=3)
m03 <- garmaFit(polio~x1+x2+x3+x4+x5, order=c(0,3), data=da, family=NBI, tail=3)
AIC(m00,m10,m01,m20,m11,m02,m30,m21,m12,m03 , k=0)
AIC(m00,m10,m01,m20,m11,m02,m30,m21,m12,m03 , k=log(168))
# without linear trend 
n00 <- garmaFit(polio~x2+x3+x4+x5, data=da, order=c(0,0), family=NBI, tail=3) # 
n10 <- garmaFit(polio~x2+x3+x4+x5, data=da, order=c(1,0), family=NBI, tail=3) # OK
n01 <- garmaFit(polio~x2+x3+x4+x5, order=c(0,1), data=da, family=NBI, tail=3)
n20 <- garmaFit(polio~x2+x3+x4+x5, order=c(2,0), data=da, family=NBI, tail=3)
n11 <- garmaFit(polio~x2+x3+x4+x5, order=c(1,1), data=da, family=NBI, tail=3)
n02 <- garmaFit(polio~x2+x3+x4+x5, order=c(0,2), data=da, family=NBI, tail=3)
n30 <- garmaFit(polio~x2+x3+x4+x5, order=c(3,0), data=da, family=NBI, tail=3)
n21 <- garmaFit(polio~x2+x3+x4+x5, order=c(2,1), data=da, family=NBI, tail=3)
n12 <- garmaFit(polio~x2+x3+x4+x5, order=c(1,2), data=da, family=NBI, tail=3)
n03 <- garmaFit(polio~x2+x3+x4+x5, order=c(0,3), data=da, family=NBI, tail=3)

AIC(m00,n10,n01,n20,n11,n02,n30,n21,n12,  k=0)
AIC(m00,n10,n01,n20,n11,n02,n30,n21,n12, k=log(168))