... ascertain the validity of the instrument in different diagnostic groups Finally, the use of DIF as a basis for analysing bias in cut points is recommended as a routine assessment where clinical cut ... passing a subtest was made through Differential Item Functioning analysis within the framework of the Rasch model [13] This analysis pooled the data from the normal and patient groups where, in ... for the MEAMS, a formal test of the validity of the cut point is the absence of DIF For example, if a cut point is set for passing a subtest and DIF is present for that subtest by age, then further...