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RE: st: Understanding Factor variables - is order significant ?
From
Richard Williams <[email protected]>
To
[email protected]
Subject
RE: st: Understanding Factor variables - is order significant ?
Date
Thu, 27 May 2010 10:31:28 -0400
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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