Nonlinear Ordinal Regression
Usage
nordr(y, dist="proportional", mu, linear=NULL, pmu,
pblock, wt=NULL, print.level=0, ndigit=10, gradtol=0.00001,
steptol=0.00001, fscale=1, iterlim=100, typsiz=abs(p),
stepmax=10*sqrt(p%*%p))
Arguments
y
|
A vector of ordinal responses, integers numbered from one to
the maximum value.
|
dist
|
The ordinal distribution: proportional odds, continuation
ratio, or adjacent categories.
|
mu
|
User-specified function of pmu , and possibly linear ,
giving the logistic regression equation. This may contain a linear
part as the second argument to the function. It may also be a language
expression beginning with ~, specifying a logistic regression function
for the location parameter. If neither is supplied, the location is
taken to be constant unless the linear argument is given.
|
linear
|
Language expression beginning with ~, specifying the
linear part of the logistic regression function.
|
pmu
|
Vector of initial estimates for the regression parameters.
|
pblock
|
Vector of initial estimates for the block parameters:
two less than the number of different ordinal values.
|
wt
|
Weight vector for use with contingency tables.
|
others
|
Arguments controlling nlm .
|
Description
nordr
fits arbitrary nonlinear regression functions (with
logistic link) to ordinal response data by proportional odds,
continuation ratio, or adjacent categories.Value
A list of class gnlr is returned.
The printed output includes the -log likelihood (not the deviance),
the corresponding AIC, the maximum likelihood estimates, standard
errors, and correlations. A list is returned that contains all of the
relevant information calculated, including error codes.Examples
# McCullagh (1980) JRSS B42, 109-142
# Tonsil size: 2x3 contingency table
y <- c(1:3,1:3)
carrier <- gl(2,3,6)
wt <- c(19,29,24,497,560,269)
pmu <- c(-1,0.5)
mu <- function(p) c(rep(p[1],3),rep(p[1]+p[2],3))
# proportional odds with mean function
nordr(y, dist="prop", mu=mu, pmu=pmu, wt=wt, pbl=1.5)
# proportional odds using Wilkinson and Rogers notation
nordr(y, dist="prop", mu=~carrier, pmu=pmu, wt=wt, pbl=1.5)
# continuation ratio
nordr(y, dist="cont", mu=mu, pmu=pmu, wt=wt, pbl=1.5)
# adjacent categories
nordr(y, dist="adj", mu=~carrier, pmu=pmu, wt=wt, pbl=1.5)