[R] Estimates for proportions

[Spencer Graves]

	  1.  If none of the numbers are 0 or 1, I might try a logit 
transformation log(p/(1-p)).  Then I'd make a normal probability plot of 
the transformed variables to check the transformation.  If that seemed 
OK., then I'd do the computations on logit space and back transform the 
result.

	  2.  If some of the numbers are 0 or 1, I'd shrink everything from 0 
and 1 using p0 = (c0+(1-2*c0)*p), then log(p0/(1-p0)).

	  Have you considered this?

hth.  spencer graves

Tanya Murphy wrote:
> Hello,
> 
> I need to get a point estimate and SD for a proportion, but the subjects' data 
> are not binary---they are proportions (of doses received). That is, I have a 
> proportion for each subject. In the past I have analysed these data as a 
> continuous (normal) variable, but I really don't want CIs over 100%. This 
> seems like basic stuff, but I don't remember learning it and it's proving 
> difficult to find (in medical statistics texts, anyway). Any pointers would be 
> greatly appreciated!
> 
> Thanks!
> 
> Tanya Murphy
> Dept. Epidemiology
> McGill University
> 
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