[Rasch] Person Misfit & Item Fit

Petroski, Greg PetroskiG at health.missouri.edu
Tue Aug 7 08:24:34 EST 2007

I am fitting a PCM and have a fairly large sample (5k).  As an
experiment I ran the calibration with all subjects and then again with
the 500 worst fitting (OUTFIT range from 2 to 9.9) individuals excluded.
There was change in parameter estimates and item fit, but not huge, not
what I expected. This is comforting, but has this been the experience of
others or is it likely just a quirk of my data and the fact that the
sample size is large to begin with?

Greg Petroski, Ph.D.
University of Missouri - Columbia

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