Score voting

Score based voting approach for voting systems


Score based voting systems, also known as evaluative or cardinal voting systems, allow voters to express the intensity of their preferences by assigning a score to each proposal. Instead of choosing a single proposal or ranking proposals in order of preference, voters rate each proposal independently on a predetermined scale.

Example score based voting systems

  • Approval Voting - Voters can vote for (approve) as many proposals as they like. The proposals with the most approvals win.

  • Disapproval Voting (Veto Voting) - Voters can vote against (veto) as many proposals as they like. The proposals with the fewest negative votes win.

  • Balanced Approval Voting - Voters can vote "yes" or "no" on each proposal. The final outcome is determined by calculating the net approval (yes votes minus no votes) for each proposal.

  • Score Voting (Range Voting) - Voters score each proposal on a scale (e.g., 0 to 5). The proposals with the highest total score win.

  • Majority Judgment - Voters grade each proposal on a scale (e.g., Excellent, Good, Fair, Poor, Very Poor). The proposal with the highest median grade wins.

  • Spend Voting - Voters have a certain number of votes they can distribute as they see fit. Voters can only spend their points once. A flexible number of votes is another variant that is occasionally used that enables voters to decide the total number of votes they want to allocate.

  • Average Voting - Each voter selects a numerical value, and the outcome is determined by calculating the average (mean) of all the votes.

  • Median Voting - Each voter selects a numerical value, and the outcome is determined by finding the median (the middle value when all votes are ordered from lowest to highest).

  • Cumulative Voting - Voters have multiple votes that they can distribute among one or more proposals as they choose. The proposals with the most votes win. The number of votes that can be distributed is often tied to the number of positions that are being filled.

  • Quadrating Voting - Voters are given a budget of credits that they can use to buy votes for proposals. The cost of each additional vote for a proposal increases quadratically, meaning the cost of a vote is equal to the number of votes squared.

  • Conviction Voting - Voters allocate points to candidates over time, reflecting the strength of their conviction. Voting participants can continuously express their support or opposition to proposals. A proposal's voting power could increase or decrease based on changes in voter support. The proposal with the most points at a given decision threshold wins.

  • Weighted Voting - Votes are weighted based on certain criteria, such as the number of shares held in a company, the population of a constituency, or other factors that assign different voting power to different voters. This approach is also a type of plurality based voting system.

  • STAR Voting (Score Then Automatic Runoff) - Voters score each candidate, such as from 0 to 5, and the top two candidates enter an automatic runoff. The candidate preferred by the majority wins in the runoff. This approach is also a type of preference based voting system.

Very high binary decision suitability (Score - 5)

  • Accuracy & expressiveness - A score based voting system could be a highly effective voting approach for a binary decision as it could capture the intensity of someone's preference. For instance if a scale of 1 to 4 was used someone could express their degree of confidence in their decision where 1 and 2 are disapproval outcomes with 1 being the highest intensity of disapproval and 3 and 4 are approval outcomes where 4 is the highest intensity of approval. Score voting could be one of the most effective approaches for increasing voter expressiveness.

  • Time required to participate - Score voting would be slightly more time consuming for voters as they would be able to express a more exact opinion. However this is still a simple approach as the voter still only has one proposal to consider and then only needs to indicate a score so the time required would not be much higher than a simple binary voting approach.

  • Voting complexity - No complex comparisons or ranking is involved and instead the voter is always just considering a single proposal and deciding on what score to give that proposal. The complexity is only slightly higher than a simple yes or no binary voting approach however the advantage is that the voting expressiveness is much higher.

Very high single selection decision suitability (Score - 5)

  • Accuracy & expressiveness - A high level of accuracy and expressiveness can be achieved with score based voting as voters are able to indicate their intensity of preference using different scores. Score based voting could be more effective than preference based voting in situations where the voting options are very different from each other as in these situations it can be more difficult to compare and rank these proposals accurately. A voter would be able to express a similar amount of preference to multiple options if they wanted to.

  • Time required to participate - Using a score based approach means that voters can select and score any of the options they want to and can choose to ignore the remaining ones. As the voter doesn’t need to compare every single proposal with other proposals this approach is effective for minimising the amount of time required for a voter to participate. For instance they could decide to just vote on a small handful of options and might prefer to leave the rest. Voters would be able to decide themselves how much time they want to spend on voting and would still be able to accurately share their preferences towards the proposals they did have time and capacity to read.

  • Voting complexity - The complexity for score based voting remains low for a single selection decision with multiple options as the scores will be aggregated to generate a fair outcome. The voter doesn’t need to rank or compare every voting option which helps to limit the complexity involved in voting.

Very high multiple selection decision suitability (Score - 5)

  • Accuracy & expressiveness - Voters could allocate their points to whichever proposals they believe are the most important. Voters can be highly expressive about their exact opinions which could be that they heavily prefer one proposal over others or that they equally prefer a number of proposals over the rest. This allocation of votes should be effective at accurately determining which proposals should be selected in a multiple selection decision.

  • Time required to participate - Voters are not forced to read and understand every proposal in the decision process to participate. They can express their preferences towards the proposals that they have read. Voters would decide themselves how much time they want to spend voting. The amount of time required would be slightly higher than a plurality voting system as the voters would also need to indicate the level of preference they have for each proposal through the score that they allocate to each proposal.

  • Voting complexity - Voters do not need to rank and compare every proposal to participate in voting. They roughly need to make comparisons to indicate their intensity of preference towards each proposal as this will determine the score they allocate to each proposal. The voter can allocate equal scores to similar proposals they prefer or they could rank them by incrementing the score as their preference increases. The complexity is slightly higher than plurality systems due to the allocation of scores to proposals, however this comes with the benefit of creating a more accurate and highly expressive voting system.

Total score = 15 / 15

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