R help - Feb 2011 - exact logistic regression

Hello to R people
Does anybody know to calculate exact logistic regression in R?
Does such option exist anywhere?
Surprisingly, could not find it using search engine. It is hard to
believe, however, that such useful function is not implemented in R yet?
Could you help, please

Thank you
Denis

Hi:

Try package elrm - its description file says that it performs exact logistic
regression by MCMC. I found this as the first set of hits I got from

# install.packages('sos')      # if necessary
library(sos)
findFn('exact logistic regression')

HTH,
Dennis

On Wed, Feb 2, 2011 at 8:43 AM, Den <d.kazakiewicz@gmail.com> wrote:
> Hello to R people
> Does anybody know to calculate exact logistic regression in R?
> Does such option exist anywhere?
> Surprisingly, could not find it using search engine. It is hard to
> believe, however, that such useful function is not implemented in R yet?
> Could you help, please
>
> Thank you
> Denis
>
> ______________________________________________
> 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.
>
	[[alternative HTML version deleted]]

Dear ?ukasz
Thank you very much for information
Dear R people could you please help please with following questions 
Sorry for my silly questions, because I am not a mathematician.
1. Is elrm() works similar as exact regression in SAS or Stata?  After
double check in Stata and R some results from my data vary greatly. 
2. How to obtain p-value from MCMClogit() from MCMCpack?

Thank you
Denis

Hate to say that, but it looks like Stata is way above R, considering
exact logistic regression.
To use elrm() I have to aggregate my data,which is really time consuming
when I look for the way out through many variables. But the worst thing
is that I am not not sure if I can  trust to p-values in output. 

I would be happy,however, if someone could contradict me on this issue.
With best regards
Denis

Dear Brad
Dear Jinko
Dear David
Sorry for the noise out of nothing.
It was because of my ignorance and misunderstanding of algorithms of
elrm.
 
elrm is great for the assessment of multivariable model where Stata
simply runs out of memory fails, while Stata can make exact calculations
on one variable.

What scared  on the first place was variation in p-values when changing
'iter' option.

Now I work with small dataset of 73 trials with 59 successes and trying
to handle with categorical independent variables. Could you please
suggest which number of iterations and burnIn is better to choose?

Could you please comment how to interpret p-value for joint effect? For
instance, I couldn't get the example in 
Zamar D, McNeney B and Graham J. elrm: Software Implementing
     Exact-like Inference for Logistic Regression Models. Journal of
     Statistical Software 2007, 21(3). 
on page 9, where p value of 0.76555 is consistent with the model used.

And finally, could you please tell if I have to cite numbers number of
iterations and burnIn in publication? 

With best regards
Denis
P.S. Sorry for naive questions




? ???, 04/02/2011 ? 14:52 -0800, Brad McNeney ????:
> You might get a more useful response if you CC the package maintainer,
David Zamar, who I don't think is a member of this list. I wonder if you
could elaborate on the reason (and provide a test data set) for your distrust of
the output.
> 
> Brad
> 
> ----- Original Message -----
> From: "Den" <d.kazakiewicz at gmail.com>
> To: "R-help" <r-help at r-project.org>
> Sent: Friday, 4 February, 2011 8:44:04 AM
> Subject: [R]  exact logistic regression
> 
> Hate to say that, but it looks like Stata is way above R, considering
> exact logistic regression.
> To use elrm() I have to aggregate my data,which is really time consuming
> when I look for the way out through many variables. But the worst thing
> is that I am not not sure if I can  trust to p-values in output. 
> 
> I would be happy,however, if someone could contradict me on this issue.
> With best regards
> Denis
> 
> ______________________________________________
> R-help at 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.