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RE: st: Understanding Factor variables - is order significant ?
From
"Feiveson, Alan H. (JSC-SK311)" <[email protected]>
To
"[email protected]" <[email protected]>
Subject
RE: st: Understanding Factor variables - is order significant ?
Date
Thu, 27 May 2010 09:38:31 -0500
The trouble with -encode- is that it puts the levels in alphabetical order. So in the L, M, H case you would get H = 1, L = 2, M = 3. To get around this you would have to define a label by hand and assign it to the string variable.
Al F.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Richard Williams
Sent: Thursday, May 27, 2010 9:31 AM
To: [email protected]
Subject: RE: st: Understanding Factor variables - is order significant ?
At 09:42 AM 5/27/2010, Ploutz-Snyder, Robert (JSC-SK)[USRA] wrote:
>Nick brings up sorting as an explanation of why to not pursue string
>variables as factor variables in Stata.
>
>If the factor variable represents an ordinal categorization, the
>analyst need merely modify his/her labels, just as now we do so by
>choosing which number represents the "first" category..etc.
>Following with Nick's example, if I wanted "low" to be first, I
>could code the values as A, B, C, and have the order that I desire.
Or, code them as "1 low" "2 medium" etc.
>Far more common, I think, are factor variables that are nominal
>instead of ordinal. Male vs. Female, Trmt vs. Control, Drug vs.
>Drug+Therapy vs. Therapy vs. Control, Race and/or Ethnicity
>categories... Those sorts of factor variables are commonly used and
>should be allowed as factor vars in Stata (as they are in other
>highly respected Stats languages).
>
>I receive/import data coded as string variables all that time, and
>to have the ability to use string vars as factors would be a much
>welcomed improvement.
I am not opposed to this, but isn't it just a matter of using a one
line -encode- command to create a numeric variable from a string variable?
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
EMAIL: [email protected]
WWW: http://www.nd.edu/~rwilliam
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