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RE: st: ttest or xtmelogit?


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: ttest or xtmelogit?
Date   Mon, 10 Mar 2008 22:02:54 -0000

By arcsin I guess you mean the angular transformation (arcsine of square
root). 
Its use seems to have faded dramatically in recent years. 

Tukey showed that this is very close to p^0.41 - (1 - p)^0.41. That
makes it weaker 
than the logit. My guess is that it would be an unusual dataset in which
the angular
was much better than leaving data as is and also much better than the
logit. It could happen, 
but it seems to be rare. 

The Tukey reference is given in -transint- from SSC. 

Nick
n.j.cox@durham.ac.uk 

David Airey

Maybe I should not have said it was pilot data! I won't disagree, but  
when cluster number is too small (< 20) to invoke xtgee or xtmelogit  
on the observed yes/no data, or glm on the summary statistics with  
binomial family and logit link, what do you do? It seems to me there  
is a sample size between 10 and 30 clusters of yes/no data that may be  
better suited to some of the older approaches like arcsin transformed  
proportions and then ttest or ANOVA/regress. I guess that was my  
question.


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