Cumulative Voting - Introduction to Cumulative Voting

Cumulative Voting

Recall cumulative voting from the cardinal voting module, it is a voting method in which voters submit fractional ballots where they split one voting among the candidates any way they like. The candidate who gets the largest sum wins.

An Example of cumulative voting

Suppose an election with candidates A , B , and C yielded the following fractional voting profile:

A gets (3 · 7/8) + (1/2) + (1/7) + (9/10) = 4.17

B gets (5 · 2/3) + (3 · 1/8) + (3/7) + (1/10) = 4.24

C gets (5 · 1/3) + (2 · 1) + (1/2) + (3/7) = 4.60

So C wins the election.

(Discrete) Cumulative Voting

  • Discrete cumulative voting is a variation of cumulative voting in which each voter gets as many votes as there are seats to be elected. If six representatives are to be elected, then the voters are each given six votes, which they can distribute any way they want. In other words, voters are essentially given one full vote that they can split into six equal parts that they can distribute how they want.

  • This variation of cumulative voting is a little bit more constraining than the cumulative fractional ballot because only fractions with denominators of six (in our case) are possible.

    • Note: The way the fractions are divided does not relate to the number of desired winners in the election.

An Example of (Discrete) Cumulative Voting

Here is an example of how a person could have voted using discrete cumulative voting for three election winners:

Add up the votes across all ballots to see who the top three scorers are:

  • A gets (5 * 1/7) + (3 * 7/7) + (1/7)= 3.86

  • B gets 1/7

  • C gets (5 * 5/7) + (1/7)= 3.71

  • D gets (5 * 1/7) + (1/7)= 0.86

  • E gets 1/7

  • F gets (2 *1/7) + (1/7)= 0.43

  • G gets (2 * 6/7) + (1/7)= 1.86

Candidates A, C and G are the election winners.

Marilyn Alberto | Jane Kinsella |Jailene Lemus