Re: st: Nominal or ordinal?

[Alan Acock <acock@mac.com>]

I don't have a hand reference, but if you generate a series of monotonic transformations of an interval scale, the linear correlations of each transformation with the interval scale variable will almost all be over .9. Of course, a non monotonic transformation would not do this, nor would it be ordinal. Also, it is possible to have an extreme monotonic transformation for which a straight line does terribly.
Alan Acock
acock@mac.com

On Aug 12, 2010, at 2:26 PM, Michael N. Mitchell wrote:

> Dear Dave (and all others)
> 
>  I know I am personally rather trusting of treating such scales as interval data... do you or any others have suggestions on references justifying the treatment of scales like this as interval?
> 
> Many thanks,
> 
> Michael N. Mitchell
> Data Management Using Stata      - http://www.stata.com/bookstore/dmus.html
> A Visual Guide to Stata Graphics - http://www.stata.com/bookstore/vgsg.html
> Stata tidbit of the week         - http://www.MichaelNormanMitchell.com
> 
> 
> 
> On 2010-08-12 1.29 PM, David Bell wrote:
>> --
>> Chelsea,
>> 
>> Most of the world is willing to treat scales like this as interval data.  Sure it isn't "exactly" interval.  Be sure to consider whether your audience will be familiar with interpretations of ordinal logit regressions.
>> 
>> Dave
>> ====================================
>> David C. Bell
>> Professor of Sociology
>> Indiana University Purdue University Indianapolis (IUPUI)
>> (317) 278-1336
>> ====================================
>> 
>> 
>> 
>> 
>> On Aug 12, 2010, at 2:59 PM, Polis, Chelsea B. wrote:
>> 
>>> Dear Statalisters,
>>> 
>>> I am working with a dependent variable that has the following four potential responses: (1) Not Likely, (2) Slightly Likely,
>>> (3) Quite Likely, (4) Extremely Likely.
>>> 
>>> A colleague thinks this is an ordinal variable which should be analyzed using ordered logit regression.  My sense was that
>>> this is a nominal variable, and should be analyzed using multinomial regression - since we cannot know if the levels are
>>> equally spaced in people's minds.
>>> 
>>> My apologies for what is probably a very simplistic question, but I've searched Statalist and online, and I still am not
>>> entirely certain.  I would greatly appreciate input on this question.
>>> 
>>> Thanks,
>>> Chelsea
>>> 
>>> 
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>> 
>> 
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