[Rasch] Rasch analysis of interval data
akyngdon at lexile.com
Wed Jul 16 23:12:48 EST 2008
I think Paul Barrett did something like this once...
Andrew Kyngdon, PhD
Senior Research Scientist
1000 Park Forty Plaza Drive
Durham NC 27713 USA
Tel. 1 919 354 3473
Fax. 1 919 547 3401
From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Anthony James
Sent: Wednesday, July 16, 2008 7:19 AM
To: rasch at acer.edu.au
Subject: [Rasch] Rasch analysis of interval data
Has anyone ever tried to Rasch analyse a variable for which there’s concatenation-based objective measurement? Suppose we make a height scale with 6 points:
Very short (1), short (2), average height (3), quite tall (4), rather all (5), Very Tall (6)
We measure some people with this scale and then Rasch analyses it and obtain Rasch height measures. How do these measures compare with persons’ heights in centimeters or inches? Does the Rasch measure difference between a person who is 170 cm and a person who is 175cm equal to the Rasch measure difference between a person who is 180cm and one who is 185cm?
I’d love to see what happens. Pairing persons’ heights in cm and their Rasch heights simultaneously on a vertical line and comparing the calibrations give a good test of Rasch’s interval scaling, I guess.
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