Displaying 20 results from an estimated 1000 matches similar to: "half-logit and glm (again)"
2012 Aug 10
0
error applying user-defined link function to lmer
Dear R users,
I'm struggling with applying a user-defined link function in lmer. For analyzing data of a 2AFC psychophysical experiment, I would like to model my binary data with a logistic function with a lower limit at 0.5 instead of 0. In a previous question this has been described as a halflogit function. To do so I wrote my own link function and would like to submit it to lmer, however
2007 Feb 10
2
error using user-defined link function with mixed models (LMER)
Greetings, everyone. I've been trying to analyze bird nest survival
data using generalized linear mixed models (because we documented
several consecutive nesting attempts by the same individuals; i.e.
repeated measures data) and have been unable to persuade the various
GLMM models to work with my user-defined link function. Actually,
glmmPQL seems to work, but as I want to evaluate a suite of
2002 Feb 27
1
Bug in glm.fit? (PR#1331)
G'day all,
I had a look at the GLM code of R (1.4.1) and I believe that there are
problems with the function "glm.fit" that may bite in rare
circumstances. Note, I have no data set with which I ran into
trouble. This report is solely based on having a look at the code.
Below I append a listing of the glm.fit function as produced by my
system. I have added line numbers so that I
2002 Mar 29
1
help with lme function
Hi all,
I have some difficulties with the lme function and so this is my problem.
Supoose i have the following model
y_(ijk)=beta_j + e_i + epsilon_(ijk)
where beta_j are fixed effects, e_i is a random effect and
epsilon_(ijk) is the error.
If i want to estimate a such model, i execute
>lme(y~vec.J , random~1 |vec .I )
where y is the vector of my data, vec.J is a factor object
2005 Jun 16
1
mu^2(1-mu)^2 variance function for GLM
Dear list,
I'm trying to mimic the analysis of Wedderburn (1974) as cited by
McCullagh and Nelder (1989) on p.328-332. This is the leaf-blotch on
barley example, and the data is available in the `faraway' package.
Wedderburn suggested using the variance function mu^2(1-mu)^2. This
variance function isn't readily available in R's `quasi' family object,
but it seems to me
2009 Nov 29
1
optim or nlminb for minimization, which to believe?
I have constructed the function mml2 (below) based on the likelihood function described in the minimal latex I have pasted below for anyone who wants to look at it. This function finds parameter estimates for a basic Rasch (IRT) model. Using the function without the gradient, using either nlminb or optim returns the correct parameter estimates and, in the case of optim, the correct standard
2015 Dec 30
1
typo in src/library/stats/man/family.Rd: names of 'validmu' and 'valideta' ??
under "Details" (version 2015-11-29 r69717; not quite cutting-edge,
but nothing has changed in src/library/stats/man/family.Rd in 5 months
[sorry for using the Github mirror, but I prefer the interface ...
<https://github.com/wch/r-source/blob/trunk/src/library/stats/man/family.Rd>])
it says:
valid.mu: logical function. Returns ?TRUE? if a mean vector ?mu? is
within the
2008 Apr 03
1
help with R semantics
Greetings:
I'm running R2.6.2 on a WinXP DELL box with 2 gig RAM.
I have created a new glm link function to be used with family = binomial.
The function works (although any suggested improvements would be welcome),
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
2009 Jul 21
0
Custom Link/Family for lmer
Hello List,
I am modeling a binomial response (nest survival) and I want to incorporate
a random effect, in this case site. I had previously been using glm with a
custom link function, but my understanding is that lmer does not currently
allow a custom link. Therefore, I was investigating if other procedures for
mixed models will allow a custom link function. here is the custom link
function:
2009 Oct 17
2
Recommendation on a probability textbook (conditional probability)
I need to refresh my memory on Probability Theory, especially on
conditional probability. In particular, I want to solve the following
two problems. Can somebody point me some good books on Probability
Theory? Thank you!
1. Z=X+Y, where X and Y are independent random variables and their
distributions are known.
Now, I want to compute E(X | Z = z).
2.Suppose that I have $I \times J$ random number
2010 Mar 26
1
Linear mixed models with custom link functions in R
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
2005 Aug 12
1
Help converting a function from S-Plus to R: family$weight
Hi all
I am converting an S-Plus function into R. The S-Plus code
uses some of the glm families, and family objects.
The family objects in S-Plus and R have many different
features, for example:
In R:
> names(Gamma())
[1] "family" "link" "linkfun" "linkinv" "variance"
[6] "dev.resids" "aic"
2005 Apr 27
0
Fitting a kind of Proportional Odds Modell using nlme, polr, lrm or ordgee
Hello,
I'm trying to fit a special kind of proportional odds model from:
Whitehead et al. (2001). Meta-analysis of ordinal outcome using
individual patient data. Statistics in medicine 20: 2243-2260. (model 2)
The data are as follows:
library(nlme)
library(geepack)
library(Design)
library(MASS)
options(contrasts=c("contr.SAS","contr.poly"))
counts <-
2002 Feb 20
2
How to get the penalized log likelihood from smooth.spline()?
I use smooth.spline(x, y) in package modreg and I would like to get
value of penalized log likelihood and preferable also its two parts. To
make clear what I am asking for (and make sure that I am asking for the
right thing) I clarify my problem trying to use the same notation as in
help(smooth.spline):
I want to find the natural cubic spline f(x) such that
L(f) = \sum_{k=1}{n} w[k](y[k] -
2005 Jun 14
1
New Family object for GLM models...
Dear R-Users,
I wish to create a new family object based on the Binomial family. The only difference will be with the link function. Thus instead if using the 'logit(u)' link function, i plan to use '-log(i-u)'.
So far, i have tried to write the function following that of the Binomial and Negative Binomial families.
The major problem i have here is with the definition of the
2012 Feb 02
0
glmer question
I would like to fit the following model:
logit(p_{ij}) = \mu + a_i + b_j
where a_i ~ N(0, \sigma_a^2) , b_j ~ N(0, \sigma_b^2) and \sigma_a
= \sigma_b.
Is it possible to fit a model with such a constraint on the variance
components in glmer?
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2008 May 20
1
"NOTE" warning
Dear all
I am using NAMESPACE in my package but I would like the user to be able
to overwrite four functions:
own.linkfun, own.linkinv, own.mu.eta and own.valideta.
These are used to defined "own" link functions.
Is there any way of doing that without getting the when I am checking
the package?
This is what I am getting:
make.link.gamlss : linkfun: no visible binding for global
2008 Jun 13
1
Writing a new link for a GLM.
Hi,
I wish to write a new link function for a GLM. R's glm routine does
not supply the "loglog" link. I modified the make.link function adding
the code:
}, loglog = {
linkfun <- function(mu) -log(-log(mu))
linkinv <- function(eta) exp(-exp(-eta))
mu.eta <- function(eta) exp(-exp(-eta)-eta)
valideta <- function(eta) all(eta != 0)
2005 Apr 14
0
predict.glm(..., type="response") dropping names (and a propsed (PR#7792)
Here's a patch that should make predict.glm(..., type="response") retain the
names. The change passes make check on our Opteron running SLES9. One
simple test is:
names(predict(glm(y ~ x, family=binomial,
data=data.frame(y=c(1, 0, 1, 0), x=c(1, 1, 0, 0))),
newdata=data.frame(x=c(0, 0.5, 1)), type="response"))
which gives
[1]
2011 Aug 26
1
matrix bands
Dear R developers,
I was looking for a function analogous to base::diag() for getting and
setting bands of a matrix. The closest I could find was Matrix::band(),
but this was not exactly what I wanted for two reasons. Firstly,
Matrix::band() returns a matrix rather than just the specified band.
Secondly, Matrix::band() cannot be used for setting the values for a
matrix band.
Setting or