Vote Unitarity is a property sequential Multi-Member System designed to ensure that voters do not get more influence that would be expected in a single member system.
Creation[edit | edit source]
Since Single Transferable Vote allocates voters it obeys vote unitarity. Reweighted Range Voting on the other hand only reduces influence fractionally so a voter who got a candidate they gave max score in the first round they ballot weight is reduced to 1/2. This violates the principle of one person one vote since this person would essentially be allowed to vote with half weight in later rounds. Proponents of Single Transferable Vote would use this argument for its superior fairness over Reweighted Range Voting. Keith Edmonds wanted to design a score reweighting system which was not simple allocation but also preserved the amount of score used through sequential rounds. He was also unhappy with Allocated Score since somebody who only gave a score of 1 to the winner could lose all future influence. Single Transferable Vote is essentially an allocation system so it also has this failing. Sequentially Spent Score is the sequential Multi-Winner Cardinal voting system built on Score voting ballots to follow this principle.