st: Rasch model INFIT

["Pritchard, Alison" <pritchard@kennedykrieger.org>]

Hello listserv members,

I am attempting to apply the Rasch model in an evaluation of intra-subtest scatter on several subtests of a common IQ measure.  I am interested in the extent to which inattention is related to an inconsistent response pattern across items within a subtest.  In order to test my hypotheses, I would like to evaluate participants' Rasch person fit indices in relation to their scores on measures of inattention.  Specifically, I am interested in the INFIT index which is available via the "raschtest" command.  My problem is that when I run the model, all participants' INFIT values come up as zero.  Any help with this would be greatly appreciated.

Thanks very much,

Alison E. Pritchard, Ph.D.
Director, Neuropsychology Research Lab
Kennedy Krieger Institute
Faculty Instructor, Department of Psychiatry & Behavioral Sciences 
Johns Hopkins School of Medicine
Phone: (443)923-4409





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