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st: RE: Re: Non parametric repeated measures

From   "Nick Cox" <>
To   <>
Subject   st: RE: Re: Non parametric repeated measures
Date   Wed, 23 Aug 2006 13:19:41 +0100

Fools rush in within such territory, but I would try 
a standard repeated measures anova on such data, 
despite the measurement scale. Then I would repeat 
that on the most nearly Gaussian equivalent of the data, 
which could be -invnormal()- applied to the ridits. The 
ridits (which have many other names) are calculated
by a function within -egenmore- from SSC. Ideally, 
there should be a consistent story. If not, the data 
may be too ornery to do much with. 

In addition, do plot the data. 


Paul Fenner
> I have been asked to analyse the following experiment The 
> outcome score is a 
> bacterial concentration scored 0 to 5. The data consists of 
> an initial 
> score, the score after treatment A and then the score after 
> treatment B. 
> This is measured on 32 subjects. The whole experiment is then 
> repeated on a 
> new set of 25 subjects but this time the sequence is initial, 
> treatment B, 
> treatment A. The null hypothesis is that the removal of bacteria is 
> independent of the treatment sequence.
> I have searched the archive but I cannot find a 
> non-parametric repeated 
> measures anova. As an alternative I can show, using the the 
> ranksum test, 
> that there there is no significant difference between the 
> three measures for 
> the two experiments but I am not happy with this as it is 
> ignoring the 
> correlated nature of the data in each experiment.
> I would be grateful for any advice on handling this data in Stata 9.2.

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