[EM] The "Single Contest" method

[Kevin Venzke]

Hi Jameson,

--- En date de : Jeu 21.7.11, Jameson Quinn <jameson.quinn at gmail.com> a écrit :
>I did have one offhand thought. If you want to propose SC for use in 
>New Zealand, perhaps you should call it Minimum Approval Opposition 
>Runoff Instant voting.

I will keep this trick in mind if I make a minimum AO runoff method.
It's not a terrible idea other than the clone issue.

>OK, on a more serious note. It seems to me that instead of using 
>ranked ballots and explicit approval cutoffs, you could use rated 
>ballots, and auto-set the global absolute approval cutoff to 
>whatever number maximizes the number of approval-decisive votes 
>in the contest.

I tried implicit approval and 3-slot. The way 3-slot worked was that
your Range vote for a given contest was equal to your highest ranking
of either candidate. Neither method was very good, because the
rankings become distorted due to the strategic considerations of the
"vote for which runoff" phase.

Your suggestion to make up the approval cutoff myself is tempting 
(because you wouldn't need approval or ratings at all) but problematic
on the strategy side. I'd certainly like a good way to make it work.
You have to be careful that you don't pick a meaningless landslide 
(e.g. everyone's fourth choice beats a write-in). You have to be sure
you don't pick a contest simply because it looks competitive (because
that tells us nothing about whether anyone is much superior). And
of course you don't want distrusting voters to compress and truncate
because of what the method may do with their rankings.

>This would probably not test as well - it's hard 
>to get simulated voters to use absolute ratings in a meaningful 
>way -

I am really curious why you say this. When my voters can rate the 
middle candidate either 33% or 67%, or 100% or 0%, they will just make
this decision based on what works the best. In 3-slot Range they very
nearly turn it into Approval. In MCA it depends on the scenario. In 
3-slot CWP they feel free to give more middle ratings.

By "meaningful" you don't mean "sincere" or something do you?

>but it would be more voter-friendly, both because empirical
>results show that rated ballots are easier, and because it 
>removes the hard-to-explain and inevitably-strategic requirement
>of setting an approval threshold. And I believe that this method
>of automatically setting the threshold would naturally find a 
>threshold that was about right - around the median of the winning 
>pair, because the median naturally has the most approval-decisive >information per ballot. I'd call this method Automatic Single 
>Contest (ASC), because Single Contest Automatic Threshold has a 
>bad acronym.

I'm interested to understand what you're proposing. You say to "auto-
set the global absolute approval cutoff to whatever number maximizes 
the number of approval-decisive votes in the contest." And you suggest
that we're putting the threshold "around the median of the winning 
pair." It seems to me this gives the method a vast amount of freedom 
to draw the thresholds. And isn't the result that you would find some
contest that is closest to 50:50 pairwise votes, and elect the winner 
of that? I think that this *would* tend to a select a halfway decent
contest, *unless* voters give you the full rankings, which is kind of
the point. I'm not going to vote "Gaddafi > Lenin" anywhere if I think
that might get picked.

Thanks.

Kevin Venzke