gnm (version 1.1-5)

asGnm: Coerce Linear Model to gnm Object

Description

asGnm is a generic function which coerces objects of class "glm" or "lm" to an object of class "gnm".

Usage

asGnm(object, ...)

Value

An object of class "gnm" - see gnm for full description.

Arguments

object

an object of class "glm" or "lm".

...

additional arguments for method functions.

Author

Heather Turner

Details

Components are added to or removed from object to produce an object of class "gnm". This can be useful in model building, see examples.

References

Vargas, M, Crossa, J, van Eeuwijk, F, Sayre, K D and Reynolds, M P (2001). Interpreting treatment by environment interaction in agronomy trials. Agronomy Journal 93, 949--960.

See Also

gnm, glm, lm

Examples

set.seed(1)

##  Scale yields to reproduce analyses reported in Vargas et al (2001)
yield.scaled <- wheat$yield * sqrt(3/1000)
treatment <- interaction(wheat$tillage, wheat$summerCrop, wheat$manure,
                         wheat$N, sep = "")
##  Fit linear model
mainEffects <- lm(yield.scaled ~ year + treatment, data = wheat)

##  Convert to gnm object to allow addition of Mult() term
svdStart <- residSVD(mainEffects, year, treatment, 3)
bilinear1 <- update(asGnm(mainEffects), . ~ . + 
                    Mult(year, treatment),
                    start = c(coef(mainEffects), svdStart[,1]))