Rasch Thresholds and Category Frequencies: what happens when Andrich Thresholds become disordered? 

Hi L. - if you mean "disordered thresholds" (caused by low frequency categories) then these are permissible according to the Rasch model and so the item fit statistics can fit. If you mean "disordered categories" (caused by higher ability persons responding in lower categories), then these contradict the Rasch model and so the items will probably misfit.