Something Fishy in American Politics

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 office, 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 8 sushi in order from best to worst.

 
 

To start, let's just have everyone vote 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.

Breaking Down the Votes

At the start, we had 5000 people rank 8 sushi in order of preference. Yet, when we tallied the votes, we only looked at each voter's top choice and ignored the bottom seven. 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 voting system — simply tallying everyone's first choice — 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.

A Different Voting System

As it turns out, the voting system you use greatly determines the outcome of the vote. Your choice of one system or another is a choice to favor certain types of candidates over others.

But 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. Let's create a dataset with only 4 sushi options. See if you can recreate the situation we saw above! Sea Urchin should win, even though more people rank it in last place. Click here to show a solution. 

 
Main Graph
Legend
 
 
Simple Vote
Simple Breakdown
 

Even with such a small number of voters and candidates, we can still have a candidate elected that the majority of people dislike! What can we do about this?

Changing the System

Right now if you vote for a losing candidate, it's easy to feel like your vote doesn't count. It'd be better if voters had a way to mark their second choice, in the event that their first choice doesn't win. Let's make a voting system that does just that. After tallying the vote, we'll remove the candidate in last place from the race, and allow those voters to pick someone else.

With the dataset of 4 candidates we created above, this might look something like this. You can click the 'Next' button to step through the system and see the new vote tally every time we remove the losing candidate.

 
Three candidate IRV.
 

That looks a lot better! Even though Sea Urchin started with the highest number of votes, it doesn't win. As the candidates are whittled down, more people prefer other candidates at least as much to Sea Urchin.

Now back to the full, 8 sushi dataset, we'll do the same thing: eliminate the worst candidate and redistribute those voters to their next favorite choice.

 
Full IRV.
 

This new system improves the situation from the beginning of the article. When the only candidates left are Tuna and Sea Urchin, the population strongly prefers Tuna — by a margin of 14%.  That's a larger margin than every US presidential race in the last 35 years! Our original plurality vote didn't show this at all!

The Take-away

We've actually created a real voting system called Ranked Choice Voting. If you place your first 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. The system prefers candidates that are well favored by the most people, rather than favoring the candidate who has the the most loyal support base. Also, Ranked Choice Voting doesn't push out third party candidates in the way that a plurality vote does. There is no "splitting" of the vote that happens, the losing candidate simply gets dropped out.

Use of the system is rare in real elections, but it's gaining steam. Recently voters in Maine chose to use Ranked Choice Voting for statewide elections, instead of Plurality.

We use Plurality Voting out of habit and out of simplicity, but that doesn't mean it's a good system. There's nothing inherently more fair about Plurality Voting, a voting system is just some method to tally the choices of voters. In fact, it's far less fair than Instant Runoff Voting on a considerable number of measures.

In an era where politics is more divisive than ever, perhaps it’s time we take a look at the systems we take for granted. The voting system we choose chooses the types of candidates we want to win. It's worth the time to think a bit about which one we prefer.

John Austin