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RE: st: Understanding Factor variables - is order significant ?


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Understanding Factor variables - is order significant ?
Date   Thu, 27 May 2010 14:20:04 +0100

I just don't think this is going to happen, regardless of the
attractions of Al's proposal. 

Here's one argument, which I guess is far from the least crucial: 

Suppose strings are permitted. Then Stata has to know what order to put
them in, if only for display purposes. Clearly, Stata's idea will be
that alphabetical order will be the obvious default. But then someone
says, "No, that's not what I want, as I have L, M, H meaning low, medium
and high, and clearly I want them in that order." Fair enough, but then
Stata needs string labels, or whatever. Except that the whole argument
can immediately be reversed. You can, long since, have numeric values
with your own text labels, so that there is, from a Stata point of view,
no need to visit this (very fundamental) change.  

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

Feiveson, Alan H. (JSC-SK311)

This again raises the issue of why Stata insists that "factor "
variables be numeric. With strings permitted as factor variables, Stata
could internally assign whatever numbers it wanted to the levels, thus
avoiding this confusion. Also a lot less bother for the user.


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