A guide to ranked voting
What is ranked voting?
Ranked voting is any vote where people put the options in order, best first, instead of picking just one. A ranking says much more than a single vote. But there's more than one way to count rankings, and they don't always agree on the winner.
Why it matters
Most votes ask one question: what's your favorite? Everything else you think goes unheard. That works fine with two options. With three or more, it causes trouble:
- Similar options split their fans. Two options that appeal to the same people divide their votes, and a third option that fewer people like can win. That's called the spoiler effect.
- Winners can be widely disliked. An option can win with the most first choices even if most people ranked it last.
- People vote strategically. Instead of voting for their favorite, people vote for whichever option they think can win, to avoid “wasting” their vote.
A ranked ballot fixes the missing information. It says what you love, what you'd be fine with and what you'd rather skip. How that information is used depends on the way the rankings are counted.
Why ranking matters
Nine friends, one dinner
Nine friends rank three restaurants, then count the very same ballots four different ways and get three different winners. This short illustrated story is the quickest way to see how the methods differ, and why the way you count matters as much as the vote.
Start the story- Chapter 1Nine friends, one dinner
- Chapter 2The elimination game
- Chapter 3The tournament
- Chapter 4Keeping score
- Chapter 5So who was right?
The ways to count
These are the most common ways to decide a single winner. Each page covers how the method works, where it came from, where it's used today, and its strengths and weaknesses.
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The baseline
Plurality voting (FPTP)
Not ranked at all: everyone picks one, and the most votes wins. Also called first past the post (FPTP). It's the method every other one is trying to improve on.
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The elimination game
Instant runoff voting (IRV)
Knock out the option with the fewest first choices and move its ballots to their next choice, until one option has a majority. Used in Australia, Ireland, Maine, New York City and at the Oscars.
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The tournament
The Condorcet method
Every option faces every other, one on one. An option that beats them all wins; loops need a tiebreaker like the Schulze method.
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Keeping score
The Borda count
Every place on a ballot is worth points, and the most points wins. Used for sports awards, the Eurovision Song Contest and top 10 lists.
How they compare
Mathematicians judge counting methods with simple fairness tests. No method passes every one, and some of these tests have been proven impossible to pass all at once. Here's how each method does.
| Fairness test | FPTP | IRV | Condorcet | Borda |
|---|---|---|---|---|
| If more than half the voters rank an option first, it winsMajority criterion | Yes | Yes | Yes | No |
| An option that beats every other one-on-one winsCondorcet criterion | No | No | Yes | No |
| Ranking a backup can't hurt your favoriteLater-no-harm | Yes* | Yes | No | No |
| More support never makes an option loseMonotonicity | Yes | No | Yes | Yes |
| Similar options don't split the voteIndependence of clones | No | Yes | Yes | No |
| Can be counted in separate places and added upSummability | Yes | No | Yes | Yes |
FPTP is plurality voting (first past the post); IRV is instant runoff voting. Condorcet results are for the Schulze method, the tiebreaker Bestof uses. *FPTP passes later-no-harm only because it never reads anything after your first choice.
Other ways to vote
- Single transferable vote (STV)
- IRV for several seats at once, used to elect Ireland's parliament and Australia's Senate. Votes beyond what a winner needs transfer to voters' next choices.
- Approval voting
- Not ranked: you mark every option you approve of, and the most approvals wins. St. Louis adopted it for city elections in 2020.
- Score voting
- Not ranked either: you rate each option, say from 0 to 5, and the highest total or average wins, like an online product review.
Questions
- Is ranked voting the same as ranked-choice voting (RCV)?
- They use the same kind of ballot. In the U.S., “ranked-choice voting” usually means one way of counting it, instant runoff voting (IRV). Ranked voting covers every way of counting ranked ballots.
- Which method is best?
- It depends on what you want. Condorcet methods and the Borda count favor options with broad support; IRV guarantees a majority in its final round; plurality (FPTP) is simplest. The last chapter of the story walks through the trade-offs.
- Do I have to rank every option?
- Usually not. Most ranked votes let you rank as many or as few as you like. What happens to the options you leave off depends on the counting method.
A guide from the makers of Bestof, an app for ranked votes with friends and family.