[EM] Instant Pairwise Elimination (IPE) vote-counting method

[VoteFair]

Here's a suggestion for an easy-to-understand vote-counting method that 
produces very fair results for single-seat elections:

Voters rank the candidates using up to 7 ranking levels (or 5 ranking 
levels if ovals are marked on a paper ballot and space is limited). 
During counting, each elimination round eliminates the candidate who 
loses every pairwise contest against every other remaining candidate. 
If an elimination round has no pairwise-losing candidate then, for that 
round, each ballot gives one count to the lowest-ranked remaining 
candidate on that ballot, and the candidate with the highest such count 
is eliminated.  The last remaining candidate wins.

Unless someone recognizes it as having a different name, I suggest 
calling it Instant Pairwise Elimination (IPE).  The word "instant" 
indicates that this method is similar to instant-runoff voting (IRV) in 
the sense of "instantly" doing multiple elimination rounds.  The word 
"pairwise" makes it clear that the eliminations use pairwise counting, 
rather than the less-fair counting method used in IRV.

This is a hybrid of Condorcet-loser elimination and the Coombs method. 
For fun, someone on Reddit (u/jpfed) suggested calling it "Coombsdorcet".

This is not a Condorcet-compliant method!  A test has already found a 
case where the IPE winner is not the Condorcet winner.  Also note that 
the description does not introduce the word Condorcet, even though it 
eliminates Condorcet losers.

I suggested it on Reddit in the r/EndFPTP subreddit because the 
single-seat voting methods being discussed there most often are 
approval, score, STAR, and IRV, which are easier to understand than 
Condorcet methods, but they have one or both of these disadvantages:

* Quite vulnerable to tactical/strategic voting

* Do not work in situations that involve general/runoff elections

The IPE method seems to be easier to explain to typical 
(non-math-oriented) voters than any of the Condorcet methods (including 
my favorite, the Condorcet-Kemeny method), yet it comes close to 
providing the fairness of Condorcet methods.

The inspiration for this method is the relative success of the STAR 
method, which is a hybrid of score and runoff.

Based on the surprisingly favorable response on Reddit, apparently most 
voters are more trusting of a method that eliminates one candidate at a 
time in a way they understand.  This contrasts with Condorcet methods, 
which can identify the winner just by "looking at" a table of pairwise 
counts.

Also, explicitly identifying "losers," and identifying them one at a 
time, seems to be emotionally appealing to voters.  Perhaps this is part 
of why IRV is seen as appealing.

Yes, this method is vulnerable to the burial tactic, at least from the 
voter's perspective.  Yet when voting methods finally get measured for 
HOW OFTEN each method fails each fairness criterion, I suspect that this 
burial-criterion failure will not affect the results often enough to be 
significant, especially compared to IRV’s frequent fairness-criteria 
failures.

In fact, the method may appeal to some voters because it will give them 
the emotional satisfaction of burying "enemy" politicians.

Please correct me if I'm wrong, but I believe that -- unlike IRV -- use 
of the IPE method would enable polling places to start by sending their 
pairwise counts to the central counting location, and the winner can be 
identified quickly in most(?) cases.  Of course some elections 
(especially if they are highly competitive) will require more ballot 
data to be sent to the central counting location before a winner can be 
calculated.  In elections that involve lots of candidates, the original 
pairwise counts might clarify the elimination sequence for the 
less-popular candidates, which would reduce the amount of ballot data 
that needs to be sent quickly to determine the winner.  By contrast, IRV 
needs almost all the raw ballot data, and the full ranking data with 
lots of candidates does not lend itself to being compressed or summarized.

According to u/Chackoony, this method is "sexier" than some other 
methods, and he says: "The future is RIPE for IPE!"

Please share your feedback about IPE, either positive or negative (or 
both).  Thanks!

Richard Fobes
Author of
Ending The Hidden Unfairness In U.S. Elections