Impact of Tie-Breaking on the Manipulability of Elections

In this paper, we quantify the impact of manipulation using the price of anarchy measurement and study the impact of the lexicographic and the random candidate tie-breaking rules. We show that neither dominates the other in terms of mitigating the impact of manipulation. Specifically, we show that the random candidate tie-breaking rule lowers the impact of manipulation in plurality elections whereas the lexicographic tie-breaking rule lowers the impact of manipulation in elections determined by majority judgment.