Recall that IRBV is the balanced version of IRV. It allows the voter to express disapproval just as easily as approval. IRBV is like IRV but the preferences are to be arranged in order of perceived importance while each must be specified either as for or against the candidate. IRBV may well have defects with regard to strategic voting that are similar to those of IRV, but those defects do seem much more difficult to tease out and any strategic voting would likely be more risky.
In the example with eleven candidates, IRBV actually could elect the consensus candidate. In that example, we might suppose that the ten candidates can be considered as five pairs of candidates, each pair representing the two sides of some issue of intense but special interest to only about 20% of the voters. If enough voters specify a preference against the candidate who opposes their position it is quite possible that one or even several of the ten candidates will, during the early rounds of counting, have negative net-vote tallies; these candidates will lose to the consensus candidate whose net vote count will only continue to increase with each round. In this way, the consensus candidate could win under IRBV but not under IRV.
Approval Voting and its balanced partner, Balanced Approval Voting, can be considered as special cases of another system of voting that is often called Range Voting. Range voting, like IRV, allows the voter the flexibility to express preferences with more granularity. The next article in this series will focus on Range Voting. Together with this present article, this next article on range voting will provide the necessary background to appreciate a new voting system that will be revealed in a second future article.
The deficiencies of IRV will be addressed once again in a future article, Isn't IRV a Great system for Voting?
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