Leading Election Systems: Pros and Cons

Leading Election Systems: Pros and Cons


Our current voting system, Plurality or First-Past-The-Post, is fatally flawed and we can do better. That much we can all agree on. So what’s the best alternative? Here we present the pros and cons of four options in detail. They are not necessarily the best four options, but they are the voting systems being compared in Oregon right now. Advocates are actively pursuing Ranked Choice (RCV) and STAR Voting (Score-Then-Automatic-Runoff). Thanks for taking the time to get educated!

 

STAR Voting:

Voters us a 5 star ballot to give each candidate a score from 0-5. The two highest scoring candidates are finalists. The finalist that was preferred by more voters wins. This is a hybrid of Score and Instant Runoff Voting which uses scoring in the first round and then implied rankings in the runoff. Your ballot already shows which finalist you preferred. It’s fine to leave candidates blank if you don’t know about them or to give multiple candidates tied scores.

Pros:

  • This is the most accurate viable system that’s been proposed according to studies by the Center For Election Science.
  • STAR Voting uses the most expressive type of ballot. Much more so than Plurality and more so than IRV. More information on the ballots allows for more accuracy.
  • Honesty is the best policy. Voters should vote their conscience.
  • Does not favor any type of voter or candidate or give anyone an unfair advantage. This is known as equal weighting of votes and it’s the legal definition of one person one vote.
  • In effect fixes the Favorite Betrayal problem from IRV and also the Strategic Voting problems from Score Voting. Using scoring in the first round and then implied ranking in the instant runoff makes STAR Voting more accurate than either scoring or ranking alone.
  • STAR Voting (SRV) is the most accurate voting system according to Voter Satisfaction Efficiency. It also does a good job of electing the Condorcet winner if one exists and offers compelling reasons why another winner was preferred by the electorate if VSE and Condorcet disagree on the best winner.
  • “[STAR Voting (SRV)] has a Voter Satisfaction Efficiency of 91% all the way up to 98%… SRV is undeniably a top-shelf election method, and arguably the best out of all the ones I tested.” -Jameson Quinn, Harvard Statistics.
  • Because STAR Voting (SRV) encourages voters to show preferences between all candidates it encourages positive, issue oriented campaigning as candidates try and get some support from their competitors constituents.
  • Passes Favorite Betrayal Criteria in practice. A voter should give their favorite a max score.
  • Allows voters to give the same score to candidates if they don’t prefer one over the other. This means that a voter can rate each candidate one by one and doesn’t have to figure out all the ratings before they can vote like is required with Ranked Choice Voting. This decreases voter burden.
  • It’s fairly simple to count and understand results. Results show total scores for each candidate and also the percentage of voters that preferred the winner over the other finalist.

Cons:

  • Voters have no incentive to be dishonest but some thought is required when deciding what scores to give candidates that aren’t your favorite or least favorite.
  • Strategic voting is possible but in the very unlikely case that a voter would benefit from tactical minimization or maximization strategy, there is no way to know which strategy would be best. In order to benefit from strategic voting a voter would need impossibly accurate polling data in a close 3 way tie scenario.
  • STAR Voting is new and hasn’t been used in a government election yet.
  • Some people are concerned that STAR Voting doesn’t always pass the controversial “Later-no-harm” Criteria, but this is actually a good thing. Later-No-Harm states that a voter should never hurt their favorite by showing support for others, but this is at direct odds with overall representative outcomes. If there is a good compromise candidate that would make voters happier overall it is good for a system to encourage voters to show that support. In practice STAR Voting does a good job at L-N-H because the odds are that showing nuanced support is more likely to help you than to hurt your favorite.
  • Ideally voters should have an informed opinion on all candidates that they prefer to their least favorite.
  • Critics worry that people could “bullet vote” giving only 5 stars or 0 stars. For some voters this is their legitimately honest effective vote, but if all voters did this STAR Voting devolves to Approval Voting, which is still a pretty good system. When voters have a more nuanced opinion they naturally want to show it. The runoff adds a huge incentive to show your preferences between each candidate so that no matter who the finalists are your vote will make a difference and help prevent your worst case scenario.

 

Instant Runoff Voting (IRV) aka Ranked Choice Voting (RCV):

Voters rank candidates on the ballot in order preference: 1st, 2nd, 3rd and sometimes more choices. If a candidate has a majority of first choice votes, that candidate wins. Otherwise, the candidate with the fewest first choice votes is eliminated. If your first choice is eliminated, your vote goes to your next choice if they haven’t been eliminated yet, and the process repeats in rounds until one candidate has a majority.

Note: RCV technically refers to all voting systems that use ranking, but in the USA RCV is often used to refer to a specific single winner version, IRV, and sometimes it’s multi winner version, STV. We discuss IRV here because it’s the most popular despite the fact that it’s the least accurate version of RCV.

Pros:

  • Fairly simple ballot.
  • Much more expressive ballot then Plurality.
  • Most voters should be honest about their rankings, particularly those that prefer frontrunners or those that have very little support.
  • Some voting machines are already coded to count the votes.

Cons:

  • Less accurate then all other voting systems covered in this article and most others according to simulated testing by the Center For Election Science.
  • Some voters will have all of their rankings counted and others will only have some of their rankings taken into account.
  • It’s not necessarily safe to vote for your favorite, there are cases where voting for your first choice is a bad strategy that can backfire when there are more than two viable candidates. (IRV fails Favorite Betrayal Criterion.) In this scenario you might want to rank your preferred front runner 1st and your favorite 2nd.
  • Doesn’t take all rankings from all ballots into account and so is not the most accurate way of counting ranked ballots. If your first choice candidate is eliminated in later rounds your second, third, or fourth choices may never be counted. (Ranked Pairs and Borda Count are much more accurate ways to count ranked ballots.)
  • IRV is vulnerable to the spoiler effect aka. vote splitting, where adding an extra candidate can cause the candidate with the most support to lose.
  • Favors voters who prefer very strong or very weak candidates but puts moderately strong candidates and their voters at a disadvantage.
  • Because you can’t give tied rankings, voters have to figure out which order to put all the candidates in before they can assign ranking. This can be tricky if you aren’t sure which you prefer or if there are similar candidates.
  • Hard for elections officials to process and understand the results because of the confusing process. Because some 2nd and 3rd choice votes are worth the same as a 1st choice vote, while others are worth nothing there’s no way to compare how many votes each candidate got at the end without re-running the whole election using another ranked choice algorithm.
  • Votes must all be processed in one central location and can’t be tabulated by precinct. This makes it more vulnerable to election fraud and is a major logistical challenge.
  • If there is a non-representative result voters may never know about it due to to complexity of results. Full data was not published for most IRV elections that have been held. Once data is published it would be up to elections officials and data analysts to crunch numbers and determine if the election picked the winner with the most support.
  • “Recent work by Robert Norman, a mathematician at Dartmouth, suggests that IRV’s …[tabulation] issues would create non-representative outcomes in one in five close contests among three candidates and that with larger numbers of candidates, it would happen even more often. The 2009 Mayoral IRV election in Burlington, Vermont was one such sideways election, and the results led to the repeal of IRV in Burlington the next year.” *
  • IRV has been repealed in x/x US cities where it’s been tried.
  • IRV puts viable 3rd parties at a strong disadvantage because that is the scenario most likely to trigger the spoiler effect or to encourage favorite betrayal strategic voting.

 

Approval Voting:

Check a box for as many candidates as you approve. The candidate with the most approval votes wins.

Pros:

  • Simple and doable using existing ballots and infrastructure.
  • Better results than Plurality Voting.

Cons:

  • Strongly favors the candidates that are perceived as most electable. This basically lets the media decide who can win, like in Plurality.
  • Doesn’t let you chose your favorite over a lesser-evil candidate so it doesn’t pass the test for honest voting.
  • Favors centrist candidates and strongly discourages 3rd party candidates.
  • Strategic Voting required for best results.
  • Doesn’t allow voters to express how they actually feel about the candidates.
  • Because voters must be strategic there is no way to know how well the results matched the actual will of the people.

 

Score Voting:

Voters give each candidate a score, the candidate with the highest total wins.

Pros:

  • Simple to understand and explain.
  • Allows voters to express detailed opinions of each candidate.
  • Simple to implement and use for elections officials and easy to understand the results.
  • Not vulnerable to favorite betrayal strategy where voters feel they have to vote for a lesser evil candidate. It’s always best to give your favorite a max score.
  • Score Voting performs well in simulations and testing and is quite accurate. Even if voters are tactical, results are still better than IRV. At the worst Score Voting is as accurate as Approval Voting, which is still a pretty good system.
  • Uses the most expressive kind of ballot which lets us accurately gauge how representative the results are.

Cons:

  • Could hypothetically be vulnerable to strategic voting tactics. Voters from the dominant parties could “bullet vote” and get an advantage by giving their favorite a max score and everyone else a zero, even if they really do have a more nuanced opinion.
  • Voters from minor parties might want to do “approval” style voting where they give their favorite a max score and also give their preferred front-runner a max score as well with zeros for all others, even if they really do have a more nuanced opinion.
  • Score Voting produces the best, most representative results if everyone shows their honest, nuanced opinion, but people can gain an individual advantage with tactical voting.

* “Frequency of monotonicity failure under Instant Runoff Voting: Estimates based on a spatial model of elections.” By Joseph T Ornstein, University of Michigan, Dept. of Political Science and Robert Z. Norman, Dartmouth College, Dept. of Mathematics

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