Displaying 7 results from an estimated 7 matches for "varfun".
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2010 Jun 17
0
Modifyiing R working matrix within "gee" source code
...,
contrasts = NULL, scale.fix = FALSE, scale.value = 1, v4.4compat =
FALSE)
{
message("Beginning Cgee S-function, @(#) geeformula.q 4.13 98/01/27")
call <- match.call()
m <- match.call(expand = FALSE)
m$R <- m$b <- m$tol <- m$maxiter <- m$link <- m$varfun <- m$corstr <-
m$Mv <- m$silent <- m$contrasts <- m$family <- m$scale.fix <- m$scale.value
<- m$v4.4compat <- NULL
if (is.null(m$id))
m$id <- as.name("id")
if (!is.null(m$na.action) && m$na.action != "na.omit") {
warn...
2019 Apr 26
1
Error in glm(..., family=quasi(..., variance=list(...)))
In a glm() call using a quasi() family, one may define a custom variance function in the form of a "list containing components varfun, validmu, dev.resids, initialize and name" (quoting the help page for family). In trying to do so, I run into the following issue that I have not seen discussed previously:
x <- runif(1000, min=0, max=1)
y <- x + rnorm(1000, mean=0, sd=1)*x^(3/4)
vf <- function(mu) { abs(mu)^(3/4)...
2012 Mar 14
1
Glm and user defined variance functions
...al
error distribution. However, I want to use an overdispersion parameter that
varies (dependent on the length of a stretch of road) so glm.nb will not do.
>From what I've read I should be able to do this using GLM by specifying my
own quasi family and describing the variance function using varfun, validmu,
dev.resids and initiate. However I cannot find any detailed discussion of
this method. Any help would be appreciated.
ps I've done this in SAS so I know it should be possible!
Craig
2007 Sep 22
0
How to explain the meaning of mu in the variance function of GLMs?
...y. The quasi family will accept the literal character
string (or unquoted as a name/expression) specifications "constant",
"mu(1-mu)", "mu", "mu^2" and "mu^3", a length-one character vector taking
one of those values, or a list containing components varfun, validmu,
dev.resids, initialize and name.
Thanks very much.
--
With Kind Regards,
oooO:::::::::
(..):::::::::
:\.(:::Oooo::
::\_)::(..)::
:::::::)./:::
::::::(_/::::
:::::::::::::
[***********************************************************************]
Zhi Jie,Zhang ,PHD
Tel:86-21-54237149
Dep...
2005 Jun 16
1
mu^2(1-mu)^2 variance function for GLM
...) NA
structure(list(family = "quasi", link = linktemp, linkfun =
stats$linkfun,
linkinv = stats$linkinv, variance = variance, dev.resids =
dev.resids,
aic = aic, mu.eta = stats$mu.eta, initialize = initialize,
validmu = validmu, valideta = stats$valideta, varfun =
variancetemp),
class = "family")
}
2005 Sep 28
1
gee models summary
I'm running some GEE models but when I request the summary(pcb.gee) all
I get are rows and rows of intercorelations and they fill up the screen
buffer so I can not even scroll back to see what else might be in the
summary. How do I get the summary function to NOT print the
intercorrelations?
Thanks,
--
Dean Sonneborn
Programmer Analyst
Department of Public Health Sciences
University of
2006 Jan 14
2
initialize expression in 'quasi' (PR#8486)
This is not so much a bug as an infelicity in the code that can easily
be fixed.
The initialize expression in the quasi family function is, (uniformly
for all links and all variance functions):
initialize <- expression({
n <- rep.int(1, nobs)
mustart <- y + 0.1 * (y == 0)
})
This is inappropriate (and often fails) for variance function
"mu(1-mu)".