[Rasch] Unidimensionality and Rasch measurement

Jim Athanasou Jim.Athanasou at uts.edu.au
Mon Jul 24 10:46:23 EST 2006


I have been asked some questions following a seminar and would 
appreciate some advice before responding.

The main question is about unidemensionality and that unidimensionality 
found in one sample may not hold elsewhere. 

Do we really have to investigate unidimensionality and then re-calibrate 
the items (and people) always starting from zero whenever we want to 
apply Rasch measurement, or, do we calibrate our scale with confidence 
on one group and then apply those findings elsewhere even in (quite) 
different populations?

Any advice would be appreciated as well as any comments on novice or 
mistaken assumptions that I have made in phrasing the questions.

Jim Athanasou

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