[Rasch] using ability estimates instead of sum scores

Fischer, Felix Felix.Fischer at charite.de
Thu Feb 11 19:04:03 EST 2010

Hello everybody,

can someone give me a hint about the effects of using ability estimates from an IRT model instead of classical derived sum scores (e.g. when using a quality of life measure)? I red that there might be a "bias", but i can't follow those advanced statistical papers in PSYCHOMETRIKA. Is it practical to just replace sum scores by ability estimates? Any literature regarding this topic would be a help, too.


Dipl. Psych. Felix Fischer
Medizinische Klinik mit Schwerpunkt Psychosomatik
Charité -- Universitätsmedizin Berlin 
Luisenstr. 13a
10117 Berlin
Tel.: 030 - 450 553575
Email: felix.fischer at charite.de

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