[Rasch] Categories too wide

Mike Linacre mike at winsteps.com
Tue Jun 11 10:21:39 EST 2013


Stuart and folks:

Not pathological. Usually the construct is defined by the hierarchy of 
item difficulties, but here the construct is defined by the hierarchy of 
category definitions. This is seen in the rating of sports and artistic 
performances in situations where the rating scales are very long, but 
the items (tasks) have a narrow difficulty range.

Mike L.

On 6/10/2013 15:37 PM, Stuart Luppescu wrote:
Hello Raschies, I remember Mike Linacre once saying something about the
situation when the step difficulties spread out much more than the item
difficulties. I have such a situation in the extreme. Between about -9
and 2 logits, the most probable response is 3. The items only vary in
difficulty between -0.6 and 0.6. Is this a
pathological condition or what?



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