EXCAT= extreme category adjustment = 0

When using Rasch measures for prediction, slightly better results have been obtained when the measure estimates are based on adjusted data. A productive adjustment makes observations in extreme categories slightly less extreme.

 

 

Example: EXCAT=0.25

 

Dichotomies: 0,1 data are analyzed as 0.25,0.75 data. The observed raw scores are the sums of these values. The category frequencies are: 0 becomes 0.75*0 and 0.25*1, 1 becomes, 0.25*0, 0.75*1.

 

Rating scale: 1,2,3,4 data are analyzed as 1.25,2,3,3.75 data. The observed raw scores are the sums of these values. The category frequencies are: 1 becomes 0.75*1 and 0.25*2, 4 becomes, 0.25*3, 0.75*4.