Hello All,
I am looking for an R library/function that allows the specification
of a custom link function in a linear mixed model. I've been using
glm() in library MASS to fit fixed-effect models with a custom link but
my study design demands mixed models. Any suggestions on the best R
library/function to achieve this would be greatly appreciated. I have
tried, to no avail, to locate a library that fits my needs by searching
CRAN and the web on the basis of which ones allow custom link
functions. Some of the mixed-effect models I'm hoping to fit involve
more than a single random factor. An example of how I've been doing
this with glm() is shown below to illustrate what I'm hoping to scale up
to a mixed model. Thanks very much for your time and thoughts.
-----------------
library(MASS)
logexp <- function(days = 1) ##Custom link function from Shaffer (2004)
Auk 121:526-540.
{
linkfun <- function(mu) qlogis(mu^(1/days))
linkinv <- function(eta) plogis(eta)^days
mu.eta <- function(eta) days * plogis(eta)^(days-1) *
.Call("logit_mu_eta", eta, PACKAGE = "stats")
valideta <- function(eta) TRUE
link <- paste("logexp(", days, ")", sep="")
structure(list(linkfun = linkfun, linkinv = linkinv,
mu.eta = mu.eta, valideta = valideta, name = link),
class = "link-glm")
}
model0 <- glm(survive~1, family=binomial(logexp(days=expos))) ##Call to
glm with custom link
---------------------
Best,
Dan Barton
--
Daniel C. Barton
PhD Candidate
USGS Montana Cooperative Wildlife Research Unit &
Program in Organismal Biology and Ecology
University of Montana
205 Natural Science
Missoula, MT 59812
daniel.bar...@umontana.edu
Missoula, MT 59812
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