Displaying 20 results from an estimated 1000 matches similar to: "spatial interaction (gravity) model as Poisson regression"
2011 Jan 03
1
Greetings. I have a question with mixed beta regression model in nlme.
*Dear R-help:
My name is Rodrigo and I have a question with nlme package
in R to fit a mixed beta regression model. The details of the model are:
Suppose that:*
*j in {1, ..., J}* *(level 1)*
*i in {1, ..., n_j}* *(level 2)*
*y_{ij} ~ Beta(mu_{ij} * phi_{ij}; (1 - mu_{ij}) * phi_{ij})
y_{ij} = mu_{ij} + w_{ij}
*
*with*
*logit(mu_{ij}) = Beta_{0i} + Beta_{1i} * x1_{ij} + b2 * x2_{ij}
2011 Jan 03
0
Greetings. I have a question with mixed beta regression model in nlme (corrected version).
*Dear R-help:
My name is Rodrigo and I have a question with nlme package
in R to fit a mixed beta regression model. I'm so sorry. In the last
email, I forgot to say that W is also a unknown parameter in the mixed
beta regression model. In any case, here I send you the correct formulation.
**
Suppose that:*
*j in {1, ..., J}* *(level 1)*
*i in {1, ..., n_j}* *(level 2)*
*y_{ij} ~
2011 Mar 31
1
rank of Matrix
Dear list,
Can anyone tell me how to obtain the rank of a sparse Matrix, for
example from package Matrix (class dgCMatrix)? Here is an example of
QR decomposition of a sparse matrix (from the sparseQR class help).
library(Matrix)
data(KNex)
mm <- KNex$mm
str(mmQR <- qr(mm))
Similarly, using the functions/classes from the relatively new
MatrixModels package:
library(MatrixModels)
2011 Jul 12
2
Deviance of zeroinfl/hurdle models
Dear list, I'm wondering if anyone can help me calculate the deviance
of either a zeroinfl or hurdle model from package pscl?
Even if someone could point me to the correct formula for calculating
the deviance, I could do the rest on my own.
I am trying to calculate a pseudo-R-squared measure based on the
R^{2}_{DEV} of [1], so I need to be able to calculate the deviance of
the full and null
2010 Jun 17
1
plotting radial dendrograms
Dear list,
I am trying to plot a radial dendrogram using the ape package, which
requires my data to be of class 'phylo'. Currently I have my
dendrogram stored as an object of class 'dendrogram' which was
produced from an outside bit of C code, but was made into an object of
class 'igraph.eigenc' and converted to a dendrogram using
'as.dendrogram()' from the igraph
2011 Feb 28
1
mixture models/latent class regression comparison
Dear list,
I have been comparing the outputs of two packages for latent class
regression, namely 'flexmix', and 'mmlcr'. What I have noticed is that
the flexmix package appears to come up with a much better fit than the
mmlcr package (based on logLik, AIC, BIC, and visual inspection). Has
anyone else observed such behaviour? Has anyone else been successful
in using the mmlcr
2011 Feb 23
0
negative binomial latent class regression in package flexmix
Hello list,
Has anyone had any luck creating an M-step driver for negative
binomial regression for use with package flexmix? I've had a look
here: http://cran.r-project.org/web/packages/flexmix/vignettes/flexmix-intro.pdf
as well as poking around in the flexmix source, but I haven't had much
luck getting anything to work. I can't figure out how to a) come up
with an initial estimate
2011 Mar 27
0
model diagnostics for MatrixModels
Dear list,
I have been working with the MatrixModels package quite a bit this
week, and it is proving to be extremely valuable for my current work
(I am working with several factors with many levels, leading to a
sparse model matrix). However, as my knowledge of statistical theory
leaves much to be desired, there are certain aspects of model
evaluation etc that I am having trouble with. Has
2011 May 26
0
'constrained' negative.binomial model estimates
Hello list,
I am not sure if the terminology that I am using here is widely used,
however, I provide an example in the hopes that my problem will become
clear. My basic problem is that I am unsure of how to 'constrain' my
model estimates to reproduce the aggregate (by factor levels) observed
dependent variable for a negative.binomial model. I realize this
sounds rather vague, so I provide
2005 Nov 20
1
Problems getting Gravity to run
Hi,
I'm having difficulties getting the news reader, Gravity, running
reliably.
Gravity installed okay, and I ran it for a single session.
During that test, the following messages appeared many times:
fixme:richedit:RichEditANSIWndProc EM_CHARFROMPOS: stub
fixme:richedit:RichEditANSIWndProc EM_LINEFROMCHAR: stub
fixme:richedit:RichEditANSIWndProc EM_LINEINDEX: stub
2008 May 05
2
Gravity (spatial interaction) models in R
I was wondering if anyone has developed (or is developing) an
implementation for gravity models (spatial interaction) in R. I
conducted several searches on the CRAN website with no luck. Currently
I am estimating parameters via linearization.
Thank you in advance
Melanie Murphy
[[alternative HTML version deleted]]
2002 Jul 01
1
Substitutions in strings.
Hi all,
Sorry to bother you with the potentially not too bright question, but
since I cannot get it to work, I'll have to ask someone..
I've got this vector:
> token
[1] sal skal skal bak b_r d_ gal kal l_r n_r pak
p_r
[13] sal sl_r sn_r spak sp_r st_r s_ bak d_ gal l_r
pak
[25] p_r sak sl_r sp_r t_ kal n_r s_ st_r sak kal
2009 Feb 08
0
Initial values of the parameters of a garch-Model
Dear all,
I'm using R 2.8.1 under Windows Vista on a dual core 2,4 GhZ with 4 GB
of RAM.
I'm trying to reproduce a result out of "Analysis of Financial Time
Series" by Ruey Tsay.
In R I'm using the fGarch library.
After fitting a ar(3)-garch(1,1)-model
> model<-garchFit(~arma(3,0)+garch(1,1), analyse)
I'm saving the results via
> result<-model
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
2010 Dec 15
0
Problems with the borders (High difficulty)
Dear r-help members,
Could any of you help me with this model, please?
This model gives error when some value touch whatever border and I do not know how to correct it. The 80% of the seeds produced by a plant will fell into the parent cell, the 15% in the first ring according to the king movement (in chess), and a 5% in the second ring defined by the queen2 matrix. Someone said me the functions
2004 Nov 23
2
IFELSE across large array?
Dear all,
As our previous email did not get any response, we try again with a
reformulated question!
We are trying to do something which needs an efficient loop over a huge
array, possibly functions such as apply and related (tapply,
lapply...?), but can't really understand syntax and examples in
practice...i.e. cant' make it work.
to be more specific:
we are trying to apply a mask
2010 Sep 08
0
Correction to vec-subset speed patch
I found a bug in one of the fourteen speed patches I posted, namely in
patch-vec-subset. I've fixed this (I now see one does need to
duplicate index vectors sometimes, though one can avoid it most of the
time). I also split this patch in two, since it really has two
different and independent parts. The patch-vec-subset patch now has
only some straightforward (locally-checkable) speedups for
2009 Oct 27
1
Rjava, RImageJ, and/or S4 question.
I am out of my league with this question. The following code starts the java imaging program ImageJ from within R, and displays an image (assuming ImageJ is installed on your computer).
library(RImageJ)
img <- IJ$openImage( file.choose() ) #pick an available .tif file
img$show() # make the image object visible
# An image is now displayed
# find out about the objects involved
>
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 Sep 29
1
generalized additive mixed models for ordinal data
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