Re: [R] Mixed-effects model for pre-post randomization design

2015-02-12 Thread Marco Barbàra
Thank you very much, Ben. Your answer has been very useful.

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Re: [R] Mixed-effects model for pre-post randomization design

2015-02-11 Thread Ben Bolker
Marco Barbàra jabbba at gmail.com writes:

 
 DeaR userRs,
 
 I recently read this Liang-Zeger article:
 
 http://sankhya.isical.ac.in/search/62b1/fpaper7.html
 
 in which (among other things) they adopt a random intercept model for
 pre-post designed trials, using a conditional likelihood approach
 (I didn't think it possible with only two measurements per subject)
 
 I'm trying to figure out (if and) how it is possible to reproduce
 straightforwardly their model using R standard mixed model tools, but
 I cannot even try to reproduce their work, since they used a
 non-available dataset (I found an extract on prof. Diggle's web site
 where it is explicitly reported to be confidential), so I have to
 review a bit of likelihood theory along with some implementation
 details.
 
 In the meantime, I wonder if anyone here could point out any related
 documentation to me.
 


  This might get more attention on r-sig-mixed-mod...@r-project.org.
I took a quick look at the paper, but it's not a case where the
answer is immediately obvious.  The paper of reference for lme4
(see http://cran.r-project.org/web/packages/lme4/citation.html )
gives technical details of lme4's implementation, in case that's
useful.


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[R] Mixed-effects model for pre-post randomization design

2015-02-11 Thread Marco Barbàra
DeaR userRs,

I recently read this Liang-Zeger article:

http://sankhya.isical.ac.in/search/62b1/fpaper7.html

in which (among other things) they adopt a random intercept model for
pre-post designed trials, using a conditional likelihood approach
(I didn't think it possible with only two measurements per subject)

I'm trying to figure out (if and) how it is possible to reproduce
straightforwardly their model using R standard mixed model tools, but
I cannot even try to reproduce their work, since they used a
non-available dataset (I found an extract on prof. Diggle's web site
where it is explicitly reported to be confidential), so I have to
review a bit of likelihood theory along with some implementation
details.

In the meantime, I wonder if anyone here could point out any related
documentation to me.

Thank you.
Marco.

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.