Supplementary vote; analysis, applications, and alternatives

The Supplementary Vote (SV) was invented as a compromise between the two-round runoff system and the alternative vote. This paper shows that in many ways it is not. Under SV voters rank order a limited number of candidates. If one candidate is supported by over 50% of the voters he/she is declared the winner. Otherwise, all but the top two candidates are eliminated from the contest. Then, all second preferences of voters are taken into account. The candidate winning most first and second votes is declared the winner. SV violates fundamental criteria used to evaluate electoral systems and is difficult for voters. The paper discusses an alternative to SV which avoids at least some of its most apparent flaws.