The point of the given transformation is not so much for normality as it is for variance stabilization. The variance of the Freeman-Tukey transform depends only on the denominator of the proportion in question...something that can be used to advantage.
Brant -----Original Message----- From: Peter Dalgaard [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 13, 2007 3:36 PM To: Bos, Roger Cc: Inman, Brant A. M.D.; r-help@stat.math.ethz.ch Subject: Re: [R] Freeman-Tukey arcsine transformation Peter Dalgaard wrote: > Bos, Roger wrote: > >> I'm curious what this transformation does, but I am not curious enough to pay $14 to find out. Someone once told me that the arcsine was a good way to transform data and make it more 'normal'. I am wondering if this is an improved method. Anyone know of a free reference? >> >> >> >> > Well, a paper copy of the American Statistician (1978) would be free in > some sense.... > > In the meantime I got detached from JSTOR (i.e., I went home), and I'm > not prepared to jump through the relevant hoops for remote access at > this point, but AFAIR it was a relatively trivial version of the simple > arcsine transform, something like replacing asin(r/n) with the average > of asin(r/(n+1)) and asin((r+1)/(n+1)). The point of the paper is that > you can invert explicitly for r/n if n is known. > > Well, except for a couple of sqrt() it seems.... >> /The American Statistician/, Vol. 32, No. 4. (Nov., 1978), >> p. 138. >> >> >> Stable URL: >> http://links.jstor.org/sici?sici=0003-1305%28197811%2932%3A4%3C138%3ATIO TFD%3E2.0.CO%3B2-Z >> >> >> > > ______________________________________________ > R-help@stat.math.ethz.ch 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. > ______________________________________________ R-help@stat.math.ethz.ch 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.