[Election-Methods] RE : Re: RE : Re: Re: rcv ala tournament

Kevin Venzke stepjak at yahoo.fr
Sun Dec 30 23:06:16 PST 2007


(Responses to Juho and Dan)

--- Juho <juho4880 at yahoo.co.uk> a écrit :
> Kevin, you maybe already know/guess my answer. B is only 2 votes  
> short of being a Condorcet winner. C would need 3 and A 5 votes.
> In your comments I note that you may think that listing a candidate  
> (higher than default bottom) has a special meaning. If there is  
> something like an implicit approval cutoff after the listed  
> candidates (=> 7 B>C>>A, 5 C>>A=B, 8 A>>B=C) then that should be  
> explicitly mentioned. The used method could in this case count both  
> the pairwise preferences and the approvals (A and C would be more  
> approved than B), and the result could be something different than  
> with pure ranking based ballots.

I think WV agrees with the voter's nature more. In Margins if the
frontrunners are A and B, and there are a bunch of other poor candidates, I
may be expected to explicitly rank the worse frontrunner in second place in
order to stop my vote from being credited to random people.

In WV I can abstain from those contests and thereby weaken their
importance. I don't think voters want to have to explicitly vote for the
worse of two frontrunners, and I don't think when they leave him and others
off they wish that this part should be filled out randomly.

(I say "randomly": On average randomly has the same effect.)

--- Dan Bishop <danbishop04 at gmail.com> a écrit :
> * If truncated ballots were disallowed and people flipped coins to 
> decide between the bottom-ranked candidates, then B wins with a 
> probability of 43.19%, compared to 30.51% for C and a mere 0.45% for A.
> * Margins makes more intuitive sense than Winning Votes.  The latter is 
> equivalent to assuming that the people who didn't vote a preference 
> between two candidates would have unanimously voted for the pairwise 
> loser.  The former is equivalent to assuming that they'd split their 
> vote equally between the two, which is MUCH more likely.

Can you explain how WV is "equivalent to assuming that the people who
didn't vote a preference between two candidates would have unanimously
voted for the pairwise loser"? Do you mean "...winner"?

To my mind, the theory behind WV is that a contest is more decisive the
more people that participate in it. Only you mustn't count the voters on
the losing side, because they could then regret expressing their opinion
rather than indifference.

>From the WV perspective one could say that margins is equivalent to
treating unspecified preferences as aiming simply to increase the effect of
those contests on the outcome.

> But I see no justification for automatically assuming that "ranked" 
> means "approved".

How is there less justification to interpret an explicit marking for a
candidate as a type of "approval," than to interpret the unspecified
preferences as explicit indifference, and using this implied explicit
indifference to elect candidates?

Note that WV doesn't actually do the former; it just doesn't violate
criteria (or offend electorates) that do. It looks safer in that respect.
If you take this election:

7 B>C
5 C
8 A

And happened to know that the C and A voters *aren't* trying to use
margins' auto-randomize feature, and were simply trying to express that
they don't like the unranked candidates, then you wouldn't want to elect B.

Now what is lost in the reverse situation (i.e. our voters are
margins-inclined) if you elect C? Are A voters really going to throw a fit
that their unspecified indifference didn't assist B?

Kevin Venzke

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