Shortlisting
Dear Colleagues,
The linked paper offers some interesting ideas related to elections, voting and social choice:
https://arxiv.org/pdf/2601.21277
Best wishes,
Joe Malkevitch
——————————————
Joseph Malkevitch
Email:
jmalkevitch@york.cuny.edu
Web page:
http://york.cuny.edu/~malk/
On 2026-01-30 18:24, Joseph Malkevitch via Election-Methods wrote:
Dear Colleagues,
The linked paper offers some interesting ideas related to elections,
voting and social choice:
https://arxiv.org/pdf/2601.21277 https://arxiv.org/pdf/2601.21277
That shortlisting is different from PR is a good point. It reminds me of
a similar thought I've been having about runoffs vs single-winner
(single-round) methods.
A single-winner method should find the best winner according to the
information provided by the ballots; or at least find a winner that can
be defended by some criteria and doesn't violate others, since "best"
may be difficult to discern due to incommensurability, etc.
But a runoff method is somewhat different. It should, I think, find a
set of candidates who could plausbly be the winner if the people were to
investigate that set more closely.
In a way, it is a shortlisting operation, but instead of using a
distinct group (the shortlisters), it instead uses noisy ballot data to
determine a set of candidates each of whom, were the noise of a
particular type, could plausibly be the winner.
The candidates continuing to the general/second round probably should
include the winner of a good single-winner ballot applied to the primary
ballots, because one model of noise is "no noise" or "whatever noise the
single-winner method can most easily handle". This immediately makes it
clear that if the single-winner method is Condorcet, then the general
election candidate set can't just be a multiwinner PR solution, since
Droop proportionality is incompatible with Condorcet.
OTOH, just picking the n highest ranked candidates according to the
single-winner method has its flaws, too: something like block ranked
pairs is really clone-dependent (just clone the RP winner n times to
fill the general).
So presumably, the solution of finding a good candidate set for a runoff
is distinct from both "just use PR" and "just use bloc results". But
what is it?
(Also, such a runoff concept would critically depend on the voters being
given more information about the candidates who win the primary so they
can refine their opinions before the general. Thus it isn't useful for
"instant" runoff methods, because there's no such period of deliberation.)
-km
What's the difference between "shortlisting" and a primary election? Isn't this essentially about ballot access?
Or, perhaps a better way to ask this: Is a primary election, which decides who are on the general election ballot (other than Independents that get ballot access directly by other means), the an implementation of "shortlisting"?
I'm not real keen about using any kind of RCV for primary elections. At least for the "Jungle primary". That opinion can change.
--
r b-j . _ . _ . _ . _ rbj@audioimagination.com
"Imagination is more important than knowledge."
.
.
.
On 2026-01-31 21:21, robert bristow-johnson via Election-Methods wrote:
What's the difference between "shortlisting" and a primary election?
Isn't this essentially about ballot access?
In the paper, shortlisting involves a "primary" by a separate group,
then the general involves everybody.
So the distinction is that my primary-general idea has lots of options
provided to the public, then the set of candidates is reduced, then the
public investigates the remaining candidates and vote again; but in
shortlisting, one group does the initial investigation (possibly more
in-depth than would be fair to ask of a large number of people) and then
another does the final one.
One example from the paper:
Example 1: Participatory Budgeting (PB) in Cambridge, MA [ 30]
receives over 1,000 project proposals in each cycle. During a four-
month Proposal Development phase, volunteer shortlisters work with
citizens and government officials to “review, research, and develop
submitted ideas to create final ballots.” They narrow down the candi-
date set according to the need, impact, and feasibility of the proposals.
Eventually, around 20 proposals are selected for a city-wide vote.
The closer this group of shortlisters is to the general population (and
drawn in an unbiased manner from it), the more shortlisting becomes like
a primary. But they don't have to be.
-km
I wouldn't rule out using some sort of proportional mechanism. It wouldn't offer "perfect" proportionality, but you could simply use a sequential "greedy" proportional method that starts off by electing to the shortlist the candidate that would win in a single-winner election.
If you use approval voting for the primary election, you could elect to the shortlist the most approved candidate. Then for the second candidate, elect the candidate with the highest approval opposition to the first. So the candidate approved on the most ballots that didn't approve the first candidate. (I got this concept from Chris Benham.) For the third candidate, would it then be logical to pick the candidate approved on the most ballots that didn't approve either of the first two? And so on. Maybe.
This could be generalised to score voting by finding at the candidate with the highest total difference to the top-scoring candidate on ballots where they score higher. Then for the third you could find the candidate with the highest total difference to the higher scoring of the top two on ballots where they outscore both. And so on.
For ranked ballots, perhaps the equivalent would be to find the candidate who has the highest number of ballots where they are ranked above the winner. Then for the third, the candidate with the highest number of ballots where they are ranked above both the top two. And so on.
Toby
On Saturday, 31 January 2026 at 20:10:03 GMT, Kristofer Munsterhjelm via Election-Methods election-methods@lists.electorama.com wrote:
On 2026-01-30 18:24, Joseph Malkevitch via Election-Methods wrote:
Dear Colleagues,
The linked paper offers some interesting ideas related to elections,
voting and social choice:
https://arxiv.org/pdf/2601.21277 https://arxiv.org/pdf/2601.21277
That shortlisting is different from PR is a good point. It reminds me of
a similar thought I've been having about runoffs vs single-winner
(single-round) methods.
A single-winner method should find the best winner according to the
information provided by the ballots; or at least find a winner that can
be defended by some criteria and doesn't violate others, since "best"
may be difficult to discern due to incommensurability, etc.
But a runoff method is somewhat different. It should, I think, find a
set of candidates who could plausbly be the winner if the people were to
investigate that set more closely.
In a way, it is a shortlisting operation, but instead of using a
distinct group (the shortlisters), it instead uses noisy ballot data to
determine a set of candidates each of whom, were the noise of a
particular type, could plausibly be the winner.
The candidates continuing to the general/second round probably should
include the winner of a good single-winner ballot applied to the primary
ballots, because one model of noise is "no noise" or "whatever noise the
single-winner method can most easily handle". This immediately makes it
clear that if the single-winner method is Condorcet, then the general
election candidate set can't just be a multiwinner PR solution, since
Droop proportionality is incompatible with Condorcet.
OTOH, just picking the n highest ranked candidates according to the
single-winner method has its flaws, too: something like block ranked
pairs is really clone-dependent (just clone the RP winner n times to
fill the general).
So presumably, the solution of finding a good candidate set for a runoff
is distinct from both "just use PR" and "just use bloc results". But
what is it?
(Also, such a runoff concept would critically depend on the voters being
given more information about the candidates who win the primary so they
can refine their opinions before the general. Thus it isn't useful for
"instant" runoff methods, because there's no such period of deliberation.)
-km
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