Displaying 20 results from an estimated 1000 matches similar to: "help with formula for clogit"
2011 Oct 27
2
help with paste
Hello gurus,
I have some variables, and i am creating combinations for analysis in the
end i need these variables to be displayed like "LEPTIN+SAA+PTH". currently
i am using loop to perform this. I would appreciate any pointers to do it
without the loop.
> mols=c("LEPTIN","SAA","PTH","sEGFR")
> samples=mols[1:3]
> samples
[1]
2002 Dec 10
3
clogit and general conditional logistic regression
Can someone clarify what I cannot make out from the
documentation?
The function 'clogit' in the 'survival' package is
described as performing a "conditional logistic regression".
Its return value is stated to be "an object of class clogit
which is a wrapper for a coxph object."
This suggests that its usefulness is confined to the sort of
data which arise in
2006 Mar 23
2
clogit question
Hi,
I am playing with
clogit(case~spontaneous+induced+strata(stratum),data=infert)
from clogit help file.
This line works.
1. But, why strata(stratum) doesn't have a coefficient like spontaneous
and induced?
2. When I remove strata(stratum) from the command, this function seems
to keep running forever. Why?
3. I think the equation for clogit looks like
P=1/(1+
2003 Jan 22
1
something wrong when using pspline in clogit?
Dear R users:
I am not entirely convinced that clogit gives me the correct result when I
use pspline() and maybe you could help correct me here.
When I add a constant to my covariate I expect only the intercept to change,
but not the coefficients. This is true (in clogit) when I assume a linear in
the logit model, but the same does not happen when I use pspline().
If I did something similar
2011 Dec 21
1
Processing time on clogit
Hi All,
I'm trying to run a conditional logistic regression in R (2.14.0) using
clogit from the survival package. The dataset I have is relatively small
(300 observations) with 25 matched strata- there are roughly 2 controls for
each case, and some strata have multiple case/control groups. When I try to
fit a very simple model with a binary outcome and a single continuous
exposure R seems to
2006 Feb 16
1
prediction function for clogit model
Dear R-Help,
I wonder if there is a prediction function for a clogit model which can be
used in the same way as the predict function for the multinom model.
In prediction('multinommodel',testset ...) it is possible to predict the
class or the class probabilities for a testset. There is a predict function
for the coxph model but I cannot find an way to use this to predict the
classes
2010 Apr 20
1
Results from clogit out of range?
Hi,
I'm calculating a conditional logit on some data stratified by group.
My understanding was that a conditional logit by definition returns a
value between 0 and 1 a a probability. Can anyone suggest why I'm
seeing results outside of the {0,1} range??
The call in R is:
m <- clogit(score ~ val_1 + val_2 + strata(group), data=data)
Then
prediction <- predict(m,newdata)
A
2011 Aug 18
4
splitting sample names
I have a data frame like this
xx<-data.frame(cbind(Sample=c('Ctrl_6h','1+0_6h','1+200_6h','1+5k_6h','Ctrl_5K_6h','ConA_6h'),
IFIT1=c(24,25,24.7,24.5,24.2,24.8)))
grep('[[:digit:]]h',xx$Sample)
yy<-xx$Sample
strsplit(yy,"_")
I have to extract the time information separated by '_' in the sample
2016 Apr 26
0
survival::clogit, how to extract residuals for GOF assessment
Hi Folks,
Hopefully this question has enough R and not too much stats to be
appropriate for this list. Based on,* Hosmer et al. 2013. Logistic
regression for matched case-control studies. Applied Logistic
Regression *(eqtn.
7.8)*, *I am assessing GOF of conditional (or matched) logistic regression
models with the *standardized Pearson residuals*. The authors define
?large? as delta chi-squared
2006 Jul 29
0
Help with clogit in survival - conditional logistic regression
Dear All:
I have been struggling to run the conditional logistic regression on a
dataset. I am using clogit function in survival package. Here is how the
data is generated. I tried to shorted the data by using the second count
variable but still the clogit did not run. Why I am not able to run clogit
on my dataset. I appreciate any input.
Regards,
Ashraf
age <- c(rep(0,8),rep(1,8))
scc <-
2008 Nov 07
0
clogit and small sample sizes: what to do?
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Hash: SHA1
Conditional logistic regression and small sample sizes: what to do?
Dear R-Gurus,
[I run R 2.8.0 on WinXP. I have no formal training in statistics.]
Please feel free to skip the 'Blah blah part' for questions below.
- ---Blah blah part--------
Why I use clogit (package 'survival')?: I am looking for risk factors
for cases during a
2004 Jun 06
0
strata() in clogit()
How can I get the log odds associated with the levels in strata()
within a clogit() model? I'm running R-1.9.0 on a Linux platform.
I am using clogit() to run a Rasch model in Item Response Theory in
psychometrics. Symbolically, the model is:
logit(p_{j,k}) = \log({\Pr(p_{j,k}) \over \Pr(1-p_{j,k})}) =
\theta_j - \alpha_k,
That is, the log odds of answering an test item correctly is
2017 Nov 13
1
Bootstrap analysis from a conditional logistic regression
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Hello
How can I perform
2006 Dec 12
1
Calculating AICc using conditional logistic regression
I have a case-control study that I'm analysing using the conditional
logistic regression function clogit from the survival package.
I would like to calculate the AICc of the models I fit using clogit.
I have a variety of scripts that can calculate AICc for models with a
logLik method, but clogit does not appear to use this method.
Is there a way I can calculate AICc from clogit in R?
Many
2011 Dec 12
1
k-folds cross validation with conditional logistic
--begin inclusion --
I have a matched-case control dataset that I'm using conditional
logistic regression (clogit in survival) to analyze. I'm trying to
conduct k-folds cross validation on my top models but all of the
packages I can find (CVbinary in DAAG, KVX) won't work with clogit
models. Is there any easy way to do this in R?
-end inclusion --
The clogit funciton is simply a
2011 Oct 17
1
calculating ratios from all combinations
so here is the code I need help to fix the line for 'st' when it reaches
maximum, that's where i am getting stuck.
thanks
Sharad
set.seed(100)
d=data.frame(x=rnorm(20)+5,
x1=rnorm(20)+5,
x2=rnorm(20)+5,
x3=rnorm(20)+5,
x4=rnorm(20)+5,
x5=rnorm(20)+5,
x6=rnorm(20)+5,
x7=rnorm(20)+5,
x8=rnorm(20)+5)
r2=c()
cinit=0
for (col in 1:9)
{
cinit=cinit+1
st=cinit+1
2011 Oct 27
2
help with parallel processing code
Hello R gurus,
I have the code below for which i need help and pointers to make it run in
parallel on a dual core win7 computer with R 2.13.x, using foreach,
iterators,doMC.
library(scatterplot3d) # Loads 3D library.
library(fields)
library(MASS)
library(ROCR)
library(verification)
library(caret)
library(gregmisc)
##simulated data
d=replicate(9, rnorm(40)+10)
2009 Jul 08
1
clogit comparison between Stata and R
Hello all
I'm moving back and forth between stata and R at the moment - of course,
using R whenever possible :-)
I'm running conditional logits on some panel data and I get slightly
different results and different N in the two programs.
In R I run
clogit(trans.dem ~ I(avg.gle_rgdp.500/gle_rgdp) + log(gle_rgdp) +
timesince.dem + I(timesince.dem^2) + timesince.dict + I(timesince.dict^2) +
2005 Dec 08
0
Assessing fit for non-nested models using clogit in survival package
I am analyzing a 1-to-2 matched case-control study using clogit in the
survival package. I am interested in comparing and assessing fit of
non-nested models. I don't want to program all the diagnostics
described in Hosmer/Lemeshow (2000). Can someone proficient with clogit
and assessing fit for non-nested models point me in the right
direction.
Many thanks!
Tomas
Tomas Aragon, MD, DrPH
Tel:
2008 Apr 25
0
function clogit
Hello,
I am using the clogit (conditional logistic regression) on a simple data set which is not related to survivorship, which I understand to be fine.
I have trouble understanding the output. I would like to find parameter estimates of the logistic models I am constructing with R, and am unclear as to what the coefficients represent that are provided.
The below is a copy of my output.