[Rasch] Item weighting for polytomies
Mike Linacre (RMT)
rmt at rasch.org
Fri Apr 30 14:17:20 EST 2010
Thank you for your questions, Gao.
The Rasch measures are based on the raw scores. Since the raw score range
for a 0,1,2,3,4,5 polytomous item is 5 times the raw score range for a 0,1
dichotomous item, the polytomous item is automatically weighted 5 times
more than the dichotomous item. Only weight the items if you do not want
the polytomous item to have 5 times the weight of the dichotomous item.
At 4/30/2010, you wrote:
>now i have a question about the item weighting issue. If the
>polychotomousy socred items are set by ISGROUP=. Say, they are have
>different score value from the dichotomously scored items. is it
>necessary to set the IWEIGHT value according to their raw scores?
>For instance, if the possible response scores for one item are
>0,1,2,3,4,5, then the weighting of that item is 5,yes?
Editor, Rasch Measurement Transactions
rmt at rasch.org www.rasch.org/rmt/ Latest RMT: 23:4 Spring 2010
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Rasch