FW: [Rasch] Constructing Variables

rsmith.arm at att.net rsmith.arm at att.net
Wed Dec 12 07:15:23 EST 2007

Dear Tom,

First, you might start with Mark Wilson's book Constructing measures: An item response modeling approach (Erlbaum).  In this case I think that the terms measures and variables are almost interchangeable. 

Second, you might look at the first paragraph inside the back cover of the Journal of Applied Measurement.  It says in part  "The construction and interpretation of meaningful and unambiguous variables is a salient feature of measurement. It represents the congruence of measurement theory and substantive research in a wide range of scientific endeavors. The development of variables that map the persons and items onto a common metric, operational defined by the items, that are invariant across samples of persons and items, is a cornerstone of developing an understanding of the phenomena being measured and the construction and verification of hypotheses based on these phenomena." 

Third, you might propose a symposium for IOMW and organize together a group of measurement experts to discuss their views of the constructing variables as opposed to accounting for sources of person variance.

Hope to see you in New York at IOMW!

Richard M. Smith, Editor 
Journal of Applied Measurement 

P.O. Box 1283 
Maple Grove, MN 55311 USA 
(JAM web site) 
voice: 763-268-2282 (w) 
fax: 763-268-2782 

-------------- Forwarded Message: -------------- 
From: "Snider-Lotz, Tom" <tsnider-lotz at previsor.com> 
To: "Rasch Mailing List (rasch at acer.edu.au)" <rasch at acer.edu.au> 
Subject: FW: [Rasch] Constructing Variables 
Date: Tue, 11 Dec 2007 15:01:59 +0000 

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
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