Commentary & Analysis

What Does “Expressiveness” Mean?

By Eric Sanders & Aaron Hamlin

So what does “expressiveness” mean in terms of voting? In our latest video and podcast, CES directors Eric Sanders and Aaron Hamlin discuss just that.

You can listen to the podcast in the following video or read the transcript below.


Eric Sanders: Eric serves on the board of directors at The Center for Election Science

Aaron Hamlin: Executive Director of The Center for Election Science


Eric: Hey everyone! I’m Eric Sanders from The Center for Election Science. I’m here with our President, Aaron Hamlin. I’m in New York City. Aaron’s in Washington, DC. How ya doin’, Aaron?

Aaron: Doing well. Thank you.

Eric: Alright, awesome. So we’re very fortunate today because we get to talk about a very important but maybe potentially easily misunderstood concept in voting theory, the concept of expressiveness. So Aaron, what do we mean when we say how expressive is a voting method? What are we talking about?

Aaron: When we’re talking about expressiveness we’re talking about the amount of information and the type of information that’s being put on a ballot which is then translated into a result.

Eric: Okay, so basically what the ballot is asking the voter to provide, what kind of information.

Aaron: Right, right. So, and generally like you mentioned, the instructions on the ballot are gonna be telling the voter what kind of information that they’re asking for. So their expression is, traditionally that’s going to be asking the voter to choose one candidate, which is our Plurality method.

Eric: Gotcha.

Aaron: But that’s not the only way though that we can express ourselves. We can express ourselves in other ways depending on what kind of ballot we have.

Eric: So different voting methods offer voters more expressiveness than just asking them to pick one candidate?

Aaron: Yeah. Absolutely. In fact, choosing one candidate is about the bare minimum as far as expressiveness goes.

Eric: So what are some other ways that we can express ourselves? What are some other examples?

Aaron: Another way would be to choose as many candidates as you want, as you approve of.

Eric: Okay, and that’s Approval Voting, right?

Aaron: Right, right. You could rank candidates. That’s another way.

Eric: And we call that Instant Runoff Voting, one of the most common names, right?

Aaron: Well, Instant Runoff Voting is a type of ranking method. There’s Condorcet methods. There’s Borda Count. There’s all different types of those.

Eric: Gotcha. But they all ask you to rank candidates. But what? There’s another way too, right, that we like?

Aaron: Right. And another way is called Score Voting which is, you’re giving your opinion, you’re expressing yourself on all the different candidates. So there’d be a scale and you would score a candidate on the given scale. And you would do that for each individual candidate. So that’s really as expressive as it gets because you’re providing a lot of information there.

Eric: Okay, so I get that different voting methods, by asking for different types and amounts of information from the voter are more or less expressive with Plurality being like the least expressive and let’s say Score being the most expressive, right?

Aaron: Right, right.

Eric: So you have a nice analogy. Would you share that with us, in terms of what expressiveness might look like?

Aaron: Sure, sure. Well, one analogy that I’ve used before is one of a sketch artist. So we’ll imagine a scenario where we’ll say that you have a loved one that’s missing. And for this example, we’ll say it’s your wife. Here, you go down to the police station and fill out a report. They take you down the hall and they introduce you to a sketch artist. And here we’ll have that sketch artist embody Plurality Voting. So the sketch artist in this situation would ask: “Okay, well. tell me the best physical feature about your wife.”

Eric: [Laughter] Okay, so he just asks you for one, pick one thing?

Aaron: Right, right. And in this case, what would you, what would you respond?

Eric: I guess I’d say her eyes.

Aaron: Her eyes. Okay. You would be describing her eyes in this situation. You would say their color, maybe their sparkle. But that would be it. So you might start to go on wanting to provide your information. [Laughter] But the sketch artist, he would, he would stop you.

Eric: Right. That’s it! That’s it! No more! That’s all you can tell me! Just the eyes! I got it! I got it! I got a great picture! I know what you want.

Aaron: [Laughter] Right, right. And so you would get a picture at the end of this.

Eric: Right. What would that? So the sketch artist turns the picture around. And what does this picture look like?

Aaron: It looks like floating eyeballs.

Eric: [Laughter] Okay, floating eyeballs. So Plurality, vote-for-one, gives us a very, would we say a very inaccurate representation of the wishes of the voter? A very unfull, a very limited perspective?

Aaron: Well it’s going to be the least amount of information possible. So you’re getting the bare minimum of information. And whether that information is even an accurate expression, as far as them being honest about that one choice, that’s issue.

Eric: Right, right.

Aaron: Even if they were being honest, it’s still, it’s the bare minimum.

Eric: So for a group of voters, for an electorate, it sounds like what you’re saying is that different voting methods, asking voters to provide more information equals an account that is potentially more representative of the overall wishes of the electorate. Is that fair to say?

Aaron: Well, you need a more expressive method to have a chance at a good outcome. But having an expressive method doesn’t necessarily mean that you’re going to have that best outcome.

Eric: Right, but would we say that it’s a necessary first step towards producing the best, the most accurate outcome possible?

Aaron: Absolutely. Because if you’re looking for a reflection of the expression from your electorate, your outcome isn’t going to be very representative of that expression if the electorate themselves can’t offer that information to begin with.

Eric: [Laughter] Gotcha. Right, so, so if we’re not asking someone to give input into all of the candidates on the ballot, how can we expect to have a sort of robust representative result at the end of the calculation of the ballots, right?

Aaron: Right, right. If you’ve got a result, that result has to come from some kind of information. It has to be calculated from something. And if you don’t provide that information to calculate that result, then, I mean, you can’t get there.

Eric: Gotcha. That makes a lot of sense. So, long story short, just going back to the analogy for one second, so with Plurality we turn it around we just see floating eyeballs. With like Approval or Score Voting, as we move up towards maximum expression, what would the picture look like?

Aaron: Well, if we’re sort of making in this analogy making it look like your wife here, it would resemble an actual person that looks like your wife.

Eric: [Laughter] Okay. So is this what we want as a voter? Do I want more expressiveness? Is this beneficial to me?

Aaron: If you want a shot at having a result that reflects the will of the electorate, then you’re gonna need to have an expressive ballot.

Eric: Ah, okay! So that makes a lot of sense. Well, awesome. Aaron, I think I have a much better sense of expressiveness. Any final thoughts? Wanna leave it at that?

Aaron: I think we can leave it at that for now. We’ll have plenty more.

Eric: I learned a lot in a few minutes. Thanks a lot.


The music in this podcast, “Parametaphoriquement,” is generously provided by gmz under a Creative Commons license, as is this podcast.