There's something very wrong with the American political system. It's understandable to be a bit tired at this point.
What if sushi ran for president, instead?
Luckily we don't have to dream — we have the data. In 2016, a researcher in Japan polled 5,000 people on their sushi habits. Each person was asked to rank 10 sushi in order from best to worst.
To start, let's just have everyone vote once for their top choice.
And the winner is! Sea Urchin?
This is a bit odd don't you think? Sea Urchin is a strong dish -- one might expect a crowd-favorite fish like tuna to come out ahead.
Let's take a deeper look.
At the start, we had 5000 people rank 10 sushi in order of preference. Yet, when we tallied the votes, we only looked at each voter's top choice and ignored the bottom nine. This missing data hides a lot.
This is what the preferences distribution looks like for each sushi. Votes towards the left means voters placed that candidate high on their list, votes on the right are from voters who placed the candidate at the bottom.
The results start to pick apart this puzzle.
Sea Urchin turns out to be quite the extremist! A great deal of people placed Sea Urchin at the top of their list, but a great deal also placed it at the bottom! In fact, even more people ranked Sea Urchin in last place than first.
And yet Sea Urchin won our first vote.
It turns out that this system of voting is just about one of the worst. It's technical name is Plurality Voting and it doesn't have a great reputation. It can often allow extremist candidates, who even a majority of people may dislike, to win elections. The system prefers candidates with a few strong supporters over candidates that are well liked by many.
As it turns out, the voting system you use greatly determines the outcome of the vote.
Voting systems aren't fixed in stone. What happens if we tweak it a bit? To do this we'll need to simplify our dataset. Here's the same dataset but with only 3 sushi options:
Changing the System
Right now, if you vote for a losing candidate, your vote essentially doesn't count. Instead, let's count all of these lost votes towards the voter's second choice.
With three candidates, this might look something like this:
If we have more than 3 candidates, we'll do the same thing: eliminate the worst candidate and redistribute those voters to the rest.
This look a lot better! This is called Instant Runoff Voting. If you place your primary vote for a candidate that doesn't win, your second and third votes get counted in the "run off" elections after your primary candidate is eliminated.
One more thing. Candidates running in a plurality vote system are often plagued by "splitting the vote". If two very similar candidates (perhaps from the same party) run in the same race, they each get half of the vote, and make things worse for the both of them. This happens all the time. It's the reason Bloomberg didn't run for president, and one reason political parties strongly tend to elect a single candidate, even when the majority of the party disagrees with their views.
Let's look at how each system handles this scenario. Click on a candidate to "clone" them. This adds a second candidate with the same view to the race (voters place this new candidate alongside the first in their ranking). We'll start with our familiar plurality system:
See if you can get a winning candidate to lose, just by adding new candidates to the race!
Now how about with Instant Runoff Voting?
It makes you wonder how we could ever trust Plurality at all.
/// todo reverse candidate breakdown to be lowest on left, highest on right
/// thoughts what are clones? make the stages clearer between irv non-started and started irv make it clear where human interaction is happening in IRV. thinks that putting too many cloned choices at the top of the ballot might throw away those votes. be clear: IRV does not allow throwing away your vote.