[EM] A better 2-round method that uses approval ballots

[Abd ul-Rahman Lomax]

At 12:44 AM 6/14/2013, Chris Benham wrote:
>
>I just want to repeat a suggestion I've made here more than 
>once.  Take my previous example where the Centre-Right candidate is 
>elected due to some of the Left candidate's supporters using the 
>Compromise strategy.
>
>49: Right
>28: Centre-Right (7 are sincere Left>Centre-Right)
>23: Left
>
>Centre-Right beats Right in the runoff 51-49.
>
>But the Right supporters have an easy Push-over strategy to (from 
>their perspective) "rectify" this.
>
>If anywhere between 6 and *all* of them change their vote to 
>approving both of Right and Left, then Left will be dragged back 
>into the runoff with Right and then be beaten.

This is the sincere stance, to be explicit:
49: Right (>? some percentage are >Centre-Right)
21: Centre-Right (>? some percentage are >Right, some are >Left)
7: Left>Centre-Right
23: Left (some percentage are Left>Centre-Right

So, we have strategic voting on the part of the Left voters already, 
in Chris's scenario. We do *not* know, from the plurality votes, who 
the best winner is. I can say that, given the Right position with 49% 
sincere first preference, Right is *almost certainly* the ideal 
winner. Right is *almost certainly* the Condorcet winner.

Chris has Centre-Right beat Right in the runoff. That is very 
unlikely to happen, at least not in the U.S. It *might happen* in a 
place with mandatory voting, but it's extremely close and risky to 
assume it will.

In the U.S., realize that we often see more than 1% write-in votes. 
Turnout is different. If it is a runoff between Right and 
Center-Right, lots of Left voters will not bother to vote, because 
they have low preference strength. On the other hand, Centre-Right 
supporters might turn out in larger numbers, having gone from 21% 
first-preference support to a runoff position. "Comeback elections" 
occur about a third of the time.

Now, what if Left makes it to the runoff. Left Voters are now highly 
motivated to turn out. Voters to the left in the Center-Right range 
of the spectrum may also be highly motivated. For a Right voter to 
assume that Right will win the runoff is also speculative.

Preference betrayal strategies are often quite risky. It would 
*never* be completely safe to vote for the total turkey, the worst 
candidate. FBC works when voting for a less evil or a compromise. Be 
careful what you ask for, Right voters, by voting for Left here, 
would be *establishing the Left party as more credible,* encouraging 
their supporters to maximally organize, and will pull some of the 
center toward the Left.

It *looks* like a coherent strategy, at first. Now, coherent 
strategies that involve preference reversal somewhat assume "owned 
voters.* They probably require coordination. And coordination on a 
large scale probably cannot happen without being visible. Such a 
strategy would *outrage* many voters. Right, if it tolerates this 
strategy, may start to lose support, even core support. So even with 
vote-for-one, Plurality, in a two-round system (top two to runoff if 
no majority), turkey-raising strategy can easily fail. It might still 
be tried. Any clear examples? I saw one election asserted that was 
*not* a clear turkey-raising strategy. It was participation in a 
Republican open primary by Democratic voters, attempting to get a 
supposed loser nominated. On closer examination, this was Democrats, 
inspired by a maverick Republican, and *neither Republican was likely 
to win.* This maverick, indeed, ended up endorsing the Democrat. And 
still got a lot of votes. He was, basically, an amazing person, a 
real Vermonter, indeed a movie version of a Vermonter, literally. 
Those Democrats who voted for him in the Republican primary would not 
have been displeased by him winning.

Now, to Chris's proposal:

>My suggested 2-round method using Approval ballots is to elect the 
>most approved first-round candidate A if A is approved on more than 
>half the ballots, otherwise elect the winner of a runoff between A 
>and the candidate that is most approved on ballots that don't show 
>approval for A.

Yeah. My general position is that runoff voting can be *vastly 
improved* by some fairly simple tweaks, or by using an advanced 
voting system, in the primary and maybe in the runoff. Approval is an 
advanced voting system *and* a tweak on Plurality.

The Arizona proposal was for nonpartisan elections, that should be 
understood. Turkey-raising strategy is thus almost certainly 
irrelevant. The proposed Arizona system is not a deterministic 
primary, it is really just a nominating procedure for the general 
election, which is then top-two Approval, simple. The general 
election is Plurality, with write-ins allowed.

It could obviously be improved with an Approval general election 
(which could allow safer write-ins) or, better, Bucklin in both. Even 
better, Bucklin using a full Range ballot, and with pairwise analysis 
to detect a Condorcet winner if different from what would otherwise 
be chosen. Another possibility would be 3-winner STV in the primary, 
with Bucklin -- same ballot -- in the general election.

>This destroys the incentive for parties to field 2 candidates, and 
>greatly reduces the Push-over incentive
>(to about the same as in normal plurality-ballot Top-2 Runoff).

Parties fielding 2 candidates is a disempowering move, in general, 
weakening campaigning. I'm generally opposed to "open primaries" in 
partisan elections. A unified primary makes sense in a non-partisan election.

And we need to understand something about nonpartisan elections. They 
are *very different* as to voter behavior from partisan elections. 
What seems to be, from the behavior of nonpartisan IRV, is that 
voters vote on name recognition and affect. It is the kind of thing 
that is heavily influenced by public exposure of the candidates, and 
it has little to do with "political position" on a spectrum. Voters 
do not appear to be voting as if there is this spectrum, with second 
preferences then being predictable from spectrum position of the 
candidates and the voter.

Rather, supporters of a candidate appear to be a fair sample of the 
*entire electorate*, and if that candidate is eliminated, these 
voters have additional preferences that reflect the *same electorate.*

I'm not seeing others repeating this concept, and it's crucial. So 
I'll state it in a different way.

If candidate A is eliminated, the ratio of second choices between B 
and C, for those who preferred A, will be the same as the ratio of 
first preferences for B and C. So IRV amalgamation does not greatly 
shift relative positions of B and C.

Hence IRV, in nonpartisan elections, tends to emulate Plurality with 
sincere votes.

Most voting system analysis assumes partisan elections, as did Chris's here.

I would conceptualize Chris's system this way. It's a 2-winner 
approval method, designed to maximize *representation* on the runoff 
ballot. Voters who approve A are already represented, so, it makes 
sense to only consider ballots not approving of A in determining the 
other runoff candidate.

However, limiting the runoff or general election ballot to two 
candidates is an unnecessary restriction. It is only a false majority 
that is created when candidates are eliminated, and, as we know, the 
pathologies of elimination systems are rooted in that elimination.

As a compromise, up to three candidates can be permitted on the 
runoff ballot, using an advanced voting system that can handle three 
candidates well, and the selection can include much better criteria 
that mere top two. If a ranked ballot with sufficient ranks is used, 
condorect winners can be identified and placed in the runoff, thus 
making the overall method condorcet compliant, i.e., a persistent 
Condorcet winner would be identified as such -- publically known -- 
and would win *unless voter preferences change or turnout shows that 
the condorcet preference strength is low.*

Another approach with a fixed general election and the primary not 
being the election, but a determination of ballot position, would be 
to run the primary as three-winner STV, with an advanced method in 
the runoff (not STV, single winner STV is atrocious.)