[Rasch] Error in CTT p-values

Anthony James luckyantonio2003 at yahoo.com
Sat Jul 25 02:52:33 EST 2009



Dear all,
The standard error for perosn raw scores under CTT is formulated as
SEM=SD*SQR(1-reliability)
I wanted to know if it is possible to estimate error for item difficulties in CTT. 
In this formula if we replace SD of person raw scores with SD of item p-values or item raw scores and then transpose the datafile and compute interperson correlations for reliability and insert it in the formula, can we say that we have estimated error in item difficulties?
I know Im under the influence of the symmetry in Rasch, not sure if it works under CTT.
Cheers
Anthony


      

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