Kway  R Documentation 
Generate and fit all 0way, 1way, 2way, ... kway terms in a glm.
This function is designed mainly for hierarchical
loglinear models (or glm
s
in the poisson family), where it is desired to find the
highestorder terms necessary to achieve a satisfactory fit.
Using anova
on the resulting glmlist
object will then give sequential tests of the pooled contributions of
all terms of degree k+1 over and above those of degree k.
This function is also intended as an example of a generating function
for glmlist
objects, to facilitate model comparison, extraction,
summary and plotting of model components, etc., perhaps using lapply
or similar.
Kway(formula, family=poisson, data, ..., order = nt, prefix = "kway")
formula 
a twosided formula for the 1way effects in the model.
The LHS should be the response, and the RHS should be the firstorder terms
connected by 
family 
a description of the error distribution and link function to be used in the
model. This can be a character string naming a family function, a family
function or the result of a call to a family function.
(See 
data 
an optional data frame, list or environment (or object coercible by

... 
Other arguments passed to 
order 
Highest order interaction of the models generated. Defaults to the number of terms in the model formula. 
prefix 
Prefix used to label the models fit in the 
With y
as the response in the formula
, the 0way (null) model
is y ~ 1
.
The 1way ("main effects") model is that specified in the
formula
argument. The kway model is generated using the formula
. ~ .^k
.
With the default order = nt
, the final model is the saturated model.
As presently written, the function requires a twosided formula with an explicit
response on the LHS. For frequency data in table form (e.g., produced by xtabs
)
you the data
argument is coerced to a data.frame, so you
should supply the formula
in the form Freq ~
....
An object of class glmlist
, of length order+1
containing the 0way, 1way, ...
models up to degree order
.
Michael Friendly and Heather Turner
glmlist
,
Summarise
(soon to be deprecated),
LRstats
## artificial data factors < expand.grid(A=factor(1:3), B=factor(1:2), C=factor(1:3), D=factor(1:2)) Freq < rpois(nrow(factors), lambda=40) df < cbind(factors, Freq) mods3 < Kway(Freq ~ A + B + C, data=df, family=poisson) LRstats(mods3) mods4 < Kway(Freq ~ A + B + C + D, data=df, family=poisson) LRstats(mods4) # JobSatisfaction data data(JobSatisfaction, package="vcd") modSat < Kway(Freq ~ management+supervisor+own, data=JobSatisfaction, family=poisson, prefix="JobSat") LRstats(modSat) anova(modSat, test="Chisq") # Rochdale data: very sparse, in table form data(Rochdale, package="vcd") ## Not run: modRoch < Kway(Freq~EconActive + Age + HusbandEmployed + Child + Education + HusbandEducation + Asian + HouseholdWorking, data=Rochdale, family=poisson) LRstats(modRoch) ## End(Not run)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.