Hi,
Charles Annis, P.E. <Charles.Annis <at> StatisticalEngineering.com> writes:
> logit.FC <- function(POD.floor = 0, POD.ceiling =1)
> { if (POD.floor < 0 | POD.floor > 1) stop ("POD.floor must be between zero
> and one.")
> if (POD.ceiling < 0 | POD.ceiling > 1) stop ("POD.ceiling must be
> between zero and one.")
> if (POD.ceiling - POD.floor < difference.criterion) stop
> (paste("POD.ceiling-POD.floor difference must be greater than
> ",difference.criterion," to discourage answer-shopping.", sep=""))
> linkfun <- function(mu) {
> mu <- qlogis( (mu - POD.floor)/(POD.ceiling - POD.floor) )
> }
> linkinv <- function(eta) {
> eta <- POD.floor + (POD.ceiling - POD.floor)*plogis(eta)
> }
> mu.eta <- function(eta) {
> (POD.ceiling - POD.floor)*dlogis(eta)# derivitaive of mu with respect to
> eta
> }
> valideta <- function(eta) TRUE
> link <- paste("logit.FC(", POD.floor, ",", POD.ceiling, ")", sep = "")
> structure(list(linkfun = linkfun, linkinv = linkinv, mu.eta = mu.eta,
> valideta = valideta, name = link), class = "link-glm")
> }
>
> Thanks.
>
> Charles Annis, P.E.
>
> <mailto:Charles.Annis <at> StatisticalEngineering.com>
> Charles.Annis <at> StatisticalEngineering.com
> phone: 561-352-9699
> eFax: 614-455-3265
> <http://www.StatisticalEngineering.com>
> http://www.StatisticalEngineering.com
>
> [[alternative HTML version deleted]]
>
I defined the following link in the psyphy package that might
be along similar lines
> probit.lambda
function (m = 2, lambda = 0)
{
m <- as.integer(m)
if (m < 2)
stop("m must be an integer > 1")
linkfun <- function(mu) {
mu <- pmax(mu, 1/m + .Machine$double.eps)
mu <- pmin(mu, 1 - lambda)
qnorm((m * mu - 1)/(m * (1 - lambda) - 1))
}
linkinv <- function(eta) {
1/m + ((m - 1)/m - lambda) * pnorm(eta)
}
mu.eta <- function(eta) ((m - 1)/m - lambda) * dnorm(eta)
valideta <- function(eta) TRUE
link <- paste("probit.lambda(", m, ",", lambda, ")", sep = "")
structure(list(linkfun = linkfun, linkinv = linkinv, mu.eta = mu.eta,
valideta = valideta, name = link), class = "link-glm")
}
<environment: namespace:psyphy>
HTH,
ken
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
