Ballot exhaustion, STV edition

In a ranked-choice election, ballot exhaustion refers to the share of ballots that do not continue to the final round of counting. A ballot exhausts because the voter has not ranked a front-runner (should one exist). Analyses of single-seat elections sometimes show that, due to ballot exhaustion, the winner was not supported by a majority of voters. According to FairVote, this has occurred in 27.6 percent of modern “instant-runoff” races (which had three or more candidates).

What about ballot exhaustion in multi-seat elections (i.e., under STV)? This is a concern for the seat-maximizing party (taken here to include multi-party coalitions and party-like entities). If ballots do not flow among co-partisans — e.g., due to bullet voting for only the most popular candidate(s) — ballot exhaustion can be blamed for having changed a seat distribution. (I will not cover vote leakage here, which is a separate but related issue.)

The plot below gives rates of ballot exhaustion for three historic cases. Two of them, Cincinnati and Worcester (MA), were the subject of my 2018 article in Electoral Studies. Robert Winters provides the data for Cambridge (MA), which still uses STV. (See this blog post, with thanks to Mirya Holman, for a sense of more recent data.)

These figures are based on total ballots cast, not the valid-ballot totals, but a quick look at the data suggests they wouldn’t change too much (although they would be somewhat higher).

Also, these figures are based on exhausted ballots from the penultimate round of counting. Why? Say we have two parties squaring off. Competition is for the final seat, which either of these can win. Computing exhaustion from the final-round count would be akin to including votes for the ‘main loser’ in an IRV contest. Neither of the papers above does this.

I make no claims about what is a “normal” rate of ballot exhaustion under STV.

That said, it is possible to speculate about the variation. Worcester likely had the highest rates due to its weak Democratic Party (i.e., one that could not, for whatever reason, deter ‘excess’ candidate entry). Another factor in at least two cites was that large numbers of independents (and the very rare third party) often (but not always) ran hopeless campaigns, and their voters do not seem to have sent votes back to the “majors” (at least in large number). In Worcester’s first election, for example, there were 152 candidates to the nine-seat council (and 126 counting rounds, due to batch elimination). In Cincinnati, by contrast, the party organizations were both strong and adept at electioneering. Also, Cincinnati was a ‘movement model’ for STV adoptions elsewhere, so people took great pains to ‘get it right.’

I say more about all this in a very big project wrapping up. If ballot exhaustion matters, there are ways to deal with it. Here’s one. Here’s another — although it is not the main reason for that proposal.

Key moving parts and 2022

Early last month, I suggested that Democrats use their trifecta to pass open-list proportional representation (OLPR). The argument for OLPR was that it would be incredibly easy to implement, i.e., it can be done in a emergency-motivated hurry. The argument for PR of any type is now familiar: partisan geography. Related to this is the need to stop/slow down realignment by retaining House control in 2022. Republican congressional obstruction will allow Republicans to claim that Democrats get nothing done, then keep chipping away at the party’s working-class base. Meanwhile, on a parallel track, continued threats to voting access make doing something even more urgent.

In short, Democrats are subject to coalition-raiding, and the overall right to vote is in danger (and has been for seven years).

A natural question to ask is: can the bleeding be stopped by retaining single-seat districts (SSD)? This is an open question. It does seem like any federal-level redistricting legislation will include “partisan fairness criteria,” i.e., provision that new maps not systematically advantage one or the other party. Here are two more relevant considerations:

1) How easy is it to draw fair SSD maps, both as a function of partisan geography, and given operational realities of redistricting within states?

2) Assuming it is doable, does this assessment account for changing district partisanship? In short, are we so far down the realignment road that “fair” districts, drawn using retrospective data, will miss the mark anyway?

As far as I know, the answer to (1) is “well, it seems doable.” With respect to (2), I have not heard anything.

Quick & dirty open-list PR allocation of 2018 US House seats

Here is what part of the US House would have looked like, 2019-20, if seats had been allocated under open-list PR based on votes in primaries. The results assume statewide allocation. I used a Hare quota and largest-remainder rule. I also removed runoffs from the data.

What is open-list PR? In this case, you vote for one candidate. This vote counts both for a person and a party.

This is not really the right way to do this. I used primary votes as a way to see how intra-party factionalism might find expression… and as a way to see what might happen if parties just ‘got rid of primaries,’ instead letting anyone who wants join the list (subject to whatever ballot access rules exist for primaries). Problems with my math are: (a) fewer people vote in primaries than generals; (b) not all districts saw primaries.

Anyway, maybe someone will find something interesting in the results. Let me know if you do!

Thanks to this crew for making the primary data available: