[Rasch] Interpreting item maps of polytomously scored items
Mike Linacre (RMT)
rmt at rasch.org
Thu Aug 24 05:36:04 EST 2006
Tom (and everybody):
The conventional definition of "item difficulty" under a polytomous Rasch
model is the point on the latent variable at which the highest and lowest
categories are equally probable. This is usually near the center of the
middle category of an odd number of categories, or close to the transition
between adjacent central categories of an even number of categories.
Tom Snider-Lotz wrote:
>My question is, what is the best statement to explain the relationship
>between a person and an polytomously-scored item when they are at the
>same spot on the logit scale?
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