Abstract
The most shortcoming of the AHP is the phenomenon of rank reversal. The ranking of alternatives determined by the AHP may be altered by addition of another alternative. The same phenomenon of rank reversal sometimes occur when irrelevant alternative are added or deleted. Unfortunately, the rank reversal occur when paired comparison matrix is entirely consistent. This report is that how the rank reversal occur when the copy alternative added to 2 alternatives or 3 alternatives in consistent condition. And we compare the conventional AHP method and the modified AHP method, which were introduced by Belton and Gear. The eigenvector are normalized which maximum eigenvector element is 1 in the modified AHP method.
