[Rasch] Threshol Disordering

Jack Stenner jstenner at lexile.com
Wed Dec 20 00:52:36 EST 2006


Ah, but Hong Kong dim sum is the best in the world. The Lexile Framework
asserts that text can be ordered on the basis of the difficulty
encountered by readers in trying to make meaning, and this ordering can
be predicted via an analysis of the semantic and syntactic features of
the text. What the Lexile analyzer reports as a measure for a piece of
text is, thanks to the symmetry of the Rasch model, the reader measure
needed to comprehend the text with 75% comprehension. But this text
measure is also something else. It is the average item difficulty
(ensemble mean) taken over all ways of turning this piece of text into a
native Lexile reading item. Anthony's 25 cloze items per passage provide
a good estimate of the ensemble distribution for each passage. The
relative ordering of the ensemble means should be predictable from the
text measure returned by the Lexile analyzer. See JAM,7(3), 307-322.
Best   Jack

-----Original Message-----
From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On
Behalf Of Trevor Bond
Sent: Monday, December 18, 2006 6:55 PM
To: Mike Linacre (RMT); rasch at acer.edu.au
Subject: Re: [Rasch] Threshol Disordering

Clearly I've eaten too many dim sum and have become a little slow.

But in what sense could a 25 response cloze passage be seen as one item
of a four item test?

With either the PCM or the RSM the model requires ordered categories.
So, surely with the RSM we must have the same 25 missing words in each
passage and in the PCM...? or we are expecting local dependence due to
one stem, so using the super- item approach?

so please tell me what I've missed . . .
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