SUSCEPTIBILITY TO MANIPULATION

All positional voting procedures can be manipulated, so it is natural to question whether some of these systems are more susceptible to being manipulated than others. In this essay, this susceptibility factor is measured for strategic action involving small groups. It is shown that the system least susceptible to micro manipulations for n = 3 candidates is the Borda Count (BC). The optimal choice changes with n, but the analysis shows that the BC always fares fairly well. On the other hand, the plurality and anti-plurality vote as well as multiple voting systems, such as approval voting and cumulative voting, always fare quite poorly with respect to susceptibility. Finally, it is shown why it is possible to justify any voting method by choosing an appropriate measure of susceptibility and imposing the appropriate assumptions on the profiles of voters. This statement emphasizes the importance of the basic assumptions of neutrality used throughout this essay. © 1990 Kluwer Academic Publishers.