Our current "Choose One" voting method, known as Plurality or First-Past-The-Post, is only fair and accurate if there are two candidates in the race. We can do better! But what’s the best alternative? Here we present the pros and cons of two leading voting methods under consideration for updating our elections.

Ranked Choice Voting has been used around the world and the states for more than a century. STAR Voting (Score Then Automatic Runoff) is a modern preference voting method that was invented to go further to deliver on the original goals, while addressing known issues with the old method.

Ranked Choice Voting and STAR have a lot in common:  Only one election is needed, primaries are optional in most cases, voters have more voice. Both are user friendly. Both can be used for single winner, multi-winner, or proportional representation elections ...

… That said, there are significant differences. 

STAR Voting: "Score - Then - Automatic - Runoff"

Voters score candidates from 0-5 stars. 5=Best, 0=Worst. Equal scores are allowed.

Ballots are counted in two rounds:

• Scoring Round: Add up all the stars from all the ballots. The two highest scoring are finalists.
• Automatic Runoff: Your one full vote goes to the finalist you scored higher. The finalist with the most votes wins. 

The two round tally works much like a primary and a top two general election all in one. The first round measures the overall support for each candidate. The second round counts how many voters prefer each finalist. 

Pros:

• The 5 star ballot is highly expressive, showing both voters level of support for each candidate and their preference order. The highly expressive ballot collects more data, and then utilizes it to maximize the election's accuracy, even in close competitive races. 
• The 5 star ballot is very user friendly. It's virtually impossible to accidentally void your ballot by filling it out incorrectly. (Unlike RCV.)
• STAR voting is the most accurate voting method according to Voter Satisfaction Efficiency (VSE) studies by the Center For Election Science. (1.)
• “[STAR Voting] has a Voter Satisfaction Efficiency of 91% all the way up to 98%… [STAR] is undeniably a top-shelf election method, and arguably the best out of all the ones I tested.” -Jameson Quinn, Harvard Statistics.
• STAR guarantees an equally weighted vote, which is the legal definition of one person one vote. This means that the voting method does not favor any type of voter or candidate or give anyone an unfair advantage. 
• STAR Voting usually elects the Condorcet winner if one exists. If VSE and Condorcet disagree on the best winner, the more expressive ballot data from the 5 star ballot showing degree of support (as well as preference) order offers compelling reasons why.
• The same Voter Satisfaction Efficiency studies showed that STAR does not incentivize strategic voting. Voters will get their best outcomes by voting their conscience.
• The best strategy with STAR is to show your preference order and level of support. As a result, STAR Voting encourages positive, issue oriented campaigning by incentivizing candidates to earn support from their competitors constituents.
• STAR 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, rather than having to figure out how they will vote on each candidate before they can start. Compared 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, much like how we vote now.
• STAR Voting ballots can be tallied locally, which is essential for high level election security. Ballots do not need to be centrally tabulated and each locality can tabulate their own ballots without losing chain of custody. This is because with STAR Voting, each round is counted using basic addition and all data on every ballot is used, unlike RCV.
• STAR Voting is compatible with Risk Limiting Audits.
• STAR Voting can be counted on most voting machines with a simple software upgrade.
• The 5 star ballot can be used for single-winner, multi-winner, or proportional representation elections.

Cons:

• STAR Voting is comparatively new and hasn’t been used in a government election yet.
• Ideally, voters should have an informed opinion on all candidates they prefer to their least favorite.
• Some thought is required when deciding what scores to give candidates who aren’t your favorite or least favorite.
  

Common criticisms:

• No voting method can completely eliminate all strategic voting. In STAR Voting it's safe and smart to give your honest favorite 5 stars, whether or not you think they can win, and to show your honest preference order. Still, less extreme types of strategic voting are still possible, though in practice they aren't exploitable. In STAR Voting, a voter considering what to score their 2nd choice might try strategically giving them a higher or lower score  (Tactical Minimization or Tactical Maximization strategy). However, in practice there is no way to know which would be best, and the two strategies would cancel each other out. In order to benefit from strategic voting a voter would need impossibly accurate polling data in a close 3 way tie scenario.
• STAR Voting doesn’t always pass the controversial “Later-no-harm” Criteria, but we believe this is actually a good thing. Later-No-Harm states that a voter will 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.
• Critics worry that people could “bullet vote” giving only 5 stars or 0 stars. For some voters this is their legitimately honest vote, but 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. If all voters Bullet Voted STAR Voting devolves to Approval Voting, which is still a pretty good system.
  

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

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 possible, and the process repeats in rounds until one candidate has a majority of the remaining votes.

Note: RCV is sometimes used to refer to both the single and multi-winner versions of the system. This article is only discussing single-winner RCV, though many of the cons can also be applied to the multi-winner versions as well. 

Pros:

• Fairly simple ranking ballot.
• Much more expressive ballot then Plurality.
• Most voters should be honest about their rankings.
• RCV is the most common alternative voting method used in the world and has 100 years of data behind it.

Cons:

• RCV is vulnerable to the spoiler effect aka. vote splitting, where adding an extra candidate can cause the candidate with the most support to lose.
• RCV tabulation makes it impossible to count ballots that give candidates equal rankings. Ballots that contain skipped rankings may or may not be countable. "We find that votes in ranked choice races are nearly 10 times more likely to be rejected due to an improper mark than votes in non-ranked choice races." 
• RCV is the least accurate voting method covered in this article according to simulated testing by the Center For Election Science.  
• RCV 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, Schultz, and Bucklin Voting are much more accurate ways to count ranked ballots.)
• Some voters will have all of their rankings counted while others will only have some of their rankings taken into account. Some voters have their first choice eliminated and their next choice isn't counted.
  
• 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. (RCV fails Favorite Betrayal Criterion.) In this scenario you might want to rank your preferred front-runner 1st and your favorite 2nd. This is particularly true if your favorite is a strong underdog who you don't think can win.
• RCV 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 has not been published for most RCV 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 RCV’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 RCV election in Burlington, Vermont was one such sideways election, and the results led to the repeal of IRV in Burlington the next year.” (1.)
  
• RCV has been repealed in a number of US cities where it’s been tried. Reasons for these repeals range from the method’s complex vote transfers, to high cost voting machine upgrades required to tally the IRV ballots, to unpopularity of the candidates elected.
  
• RCV 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.

1.) “[IRV] can cause spoilers in up to 1 in 5 elections or worse when there are more candidates according to expert analysis.” 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 https://www.researchgate.net/publication/258164743_Frequency_of_monotonicity_failure_under_Instant_Runoff_Voting_Estimates_based_on_a_spatial_model_of_elections

2.) Ballot (and voter) “exhaustion” under Instant Runoff Voting: An examination of four ranked-choice elections. "The rate of ballot exhaustion was high in each election, ranging 9.6%–27.1%." By Craig M. Burnett, University of North Carolina, and Vladimir Kogan, Ohio State University, USA. https://www.sciencedirect.com/science/article/abs/pii/S0261379414001395

3.) Voter Participation with Ranked Choice Voting in the United States. By David C. Kimball and Joseph Anthony, Department of Political Science University of Missouri‐St. Louis St. Louis, MO. "We find that RCV helps reduce the substantial drop in voter participation that commonly occurs between primary and runoff elections. Otherwise RCV does not appear to have a strong impact on voter turnout and ballot completion. In a case study of Minneapolis we find similar levels of socioeconomic and racial disparities in voter participation in plurality and RCV elections." https://www.umsl.edu/~kimballd/KimballRCV.pdf

4.) Expert report reveals weaknesses of RCV. By Isabelle Christie. "Drawing on previous research conducted by the Maine Policy Institute, McCarty examined 98 RCV elections from 2006 to 2019 and found that, on average, 10.8 percent of ballots casted were considered exhausted by the final round."

5.) Overvoting and the Equality of Voice under Instant-Runoff Voting in San Francisco, California Journal of Politics and Policy. By Francis Neely and Jason A. McDaniel San Francisco State University. "Concerns about the fairness of IRV led at least four jurisdictions to repeal similar reforms shortly after enacting them: Burlington, VT (2006–2009), Cary, NC (2007–2009), Pierce County, WA (2006–2009), Aspen, CO (2009)." and "Consistently, precincts where more African-Americans reside are more likely to collect overvoted, voided ballots. And this often occurs where more Latino, elderly, foreign-born, and less wealthy folks live."

6.) Voter Satisfaction Efficiency (VSE) studies by Dr Jameson Quinn Phd. At the time this study was released Quinn was Vice Chair for the Center for Election Science. Quinn is now on the board of the Equal Vote Coalition http://electionscience.github.io/vse-sim/vse.html