Statalist The Stata Listserver

[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

RE: st:Transformation for skewed variables with negative values?

From   "Nick Cox" <>
To   <>
Subject   RE: st:Transformation for skewed variables with negative values?
Date   Tue, 15 Aug 2006 22:58:43 +0100

Also, partially echoing Jeph Herrin, if everything is negative, 
consider reversing signs. Sign is often a convention. 

However, I would want really good grounds 
for shifting origins, even if the origin were conventional. 
That is, if x everywhere is greater than a, then (x - a) is 
positive, but if a is just empirically determined, it can be 
difficult to interpret (x - a) or to compare results with other 


> I agree with Joseph's general stance on this question. 
> Also, consider the alternative of a non-identity link 
> and a -glm-, which often offers the advantages of
> a transformation without the disadvantages. 
> However, more generally, I will add a plug for 
> my package -transint- from SSC, which is just 
> a help file with various comments on transformations. 
> You can install it using -ssc-. 

*   For searches and help try:

© Copyright 1996–2015 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index