With N candidates, there are (N x (N-1))/2 pairings. N Pairings 2 1 3 3 4 6 5 10 6 15 It is obviously easier to do N rankings than to do the (N x (N-1))/2 pairings. Example- With N=5, it is obviously easier for a voter to put 5 rankings on a ballot rather than vote on all 10 pairings.