[Rasch] Constructing Variables

Tim Pelton tpelton at uvic.ca
Wed Dec 12 04:09:14 EST 2007


Good question... I haven't a paper to point you to, but I'll share my  
interpretation.

 From my programming roots I see the word 'variable' as a bucket to  
put a value that might be manipulated or measured.

 From my elementary math education roots, I see the word 'attribute'  
as descriptor of quantitative or qualitative feature of some 'thing'  
that we are  measuring, observing or manipulating.  The use of  
'variable' in the context of latent/hidden/obscured/anticipated/ 
theoretical quantitative 'attributes' seems appropriate because we  
are trying to measure and manipulate something that we believe can be  
linked to a numerical scale (either extensive or intensive)

The word 'construct' I link to Seymor Papert's idea of  
constructionism ( "Giving children good things to do so that they can  
learn by doing much better than they could before." - http:// 
www.papert.org/articles/const_inst/const_inst1.html) which when  
transfered to our 'adult' world of learning means that we are  
engaging in a  thoughtful and creative process that allows us to make  
some sense of, and measure, latent quantitative attributes in our  
area of interest.

So 'Constructing Variables' to me then seems like a learning process  
to develop theories about latent quantitative attributes in some  
chosen context and to support those theories with evidence by  
manipulating or objectively observing values or variables within that  
context.

Tim


On 11-Dec-07, at 7:01 AM, Snider-Lotz, Tom wrote:

> Hello all --
>
> I'm a bit surprised at the lack of response to my question (below)  
> about constructing variables.  I'd thought this would be an easy  
> one!  In place of a lengthy answer, I'd be grateful for a reference  
> that I could follow up.
>
> Thanks, all.
>
>  -- Tom
>
> From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au]  
> On Behalf Of Snider-Lotz, Tom
> Sent: Friday, December 07, 2007 11:55 AM
> To: Rasch Mailing List (rasch at acer.edu.au)
> Subject: [Rasch] Constructing Variables
>
> The IOMW conference next March looks very interesting, but I must  
> admit that I don't understand the theme, "Constructing Variables."   
> I know this is a common phrase in the Rasch world, and has been the  
> theme for several issues of the Journal of Applied Measurement --  
> but still I don't know quite what it means.  What is the difference  
> between a constructed variable and one that's not constructed?   
> What's involved in constructing a variable?  If I run test results  
> through Winsteps, are the item measures constructed variables?
>
> I work in employment selection testing, and when I think of  
> variables I think of test scores, supervisory ratings of  
> performance, number of words typed per minute, number of units  
> sold, and so forth.  Would these be included in the domain of  
> variables to be discussed at this conference, and are any of them  
> "constructed"?
>
> Thanks for any clarification you might offer.
>
>   -- Tom  
> Snider<ATT00001.txt>_______________________________________________
> Rasch mailing list
> Rasch at acer.edu.au
> http://mailinglist.acer.edu.au/mailman/listinfo/rasch

---
Tim Pelton,
Department of Curriculum and Instruction
University of Victoria
PO Box 3010 STN CSC
Victoria BC V8W 3N4
tel 250-721-7803, fax 250-721-7598
---
Intuition is unarticulated theory based upon experience...sometimes  
these theories are good and sometimes they are not.


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