[Election-Methods] RE : Corrected "strategy in Condorcet" section

[Juho]

On Aug 12, 2007, at 20:04 , Kevin Venzke wrote:

>>> I think margins does give a clear reason to not vote for weak
>>> candidates,
>>> especially if there's a chance they're strong enough to get a  
>>> pairwise
>>> win.
>>
>> I still miss the concrete waterproof example. (Sorry if I should have
>> known which one it is.)
>
> Another example? The 49 24 27 scenario shows that margins can do this.

Yes, that scenario shows that in some situations some strategies work  
in margins but not in winning votes. Sorry about my unclear  
expression. I'm trying to find examples that would be damaging to  
margins in the sense that they would occur often in typical  
elections, would be risk free to strategists, easy to implement,  
tolerable to measurement errors etc. And I tried to pinpoint  
weaknesses in the presented scenarios (why they would no be as big a  
threat as the extreme/theoretical cases first seem to indicate.)

> If you believe your favorite candidate is strong enough to beat the
> better frontrunner but not strong enough to win, you shouldn't vote  
> for
> him. It's not even safe enough to rank them equally, since you might
> need to compensate for voters with the same preferences you have  
> but who
> are choosing to vote sincerely.

I'll try to find some (more) problem free set of votes for such a  
situation. (Success not guaranteed.)

> You frequently say that conditions are so uncertain that who can say
> whether a strategy is good to use. But surely voters will at least  
> believe
> they can gauge whether their favorite candidate is likely to win.

Often that may be the case, but it is also quite typical to elections  
that the winner and/or #2 are not known beforehand. And individual  
voters often have different understanding, and all the candidates  
claim to be close to winning. It is also possible that voters vote  
against "pre-declared" winners.

> The WV strategy proposal didn't involve bullet voting. The whole point
> is that it didn't involve bullet voting.

Didn't quite get this. I used bullet voting as a synonym to  
truncation in a three candidate race.

>>>> Yes, I meant sincere voting in Condorcet. I don't believe I can
>>>> provide you a method that would be immune to strategic voting,  
>>>> but I
>>>> do believe that in some environments most people would vote  
>>>> sincerely
>>>> anyway. This is because on average sincere voting can be claimed to
>>>> bring them the best results.
>>>
>>> This is not really true with respect to votes for candidates that
>>> you do
>>> not think can win.
>>
>> True for candidates that have no chances.
>
> And this is a problem. Voters shouldn't have to weed weak  
> candidates out
> of their ranking before they vote. The method should just ignore those
> candidates.

Planning to analyse this with "realistic" votes.

> With Condorcet there is a big difference that candidates you're better
> off truncating when there's only one round, are *perfectly safe* to  
> vote
> for if there's a second round with just two contenders.

Ok, the first and second rounds are different and different  
strategies may apply - both in two-round runoff and "two-stage  
Condorcet". Also here I don't want to throw in a generic judgement  
that would cover all cases but plan to approach the threat level of  
the scenarios (that exist) via concrete and hopefully realistic  
examples.

> In the first round you vote FOR one candidate. You also vote  
> AGAINST one
> candidate. If someone has more than half of the FOR votes, they are
> elected. If someone has more than half of the AGAINST votes, they are
> disqualified. Then the second round is between the two candidates with
> the most FOR votes who have not been disqualified.

I'm always a bit careful with the "against" votes. If there are e.g.  
three strong parties the supporters of the other parties might vote  
the candidate of one party out. In this situation it is also possible  
that some unknown candidate or a candidate that nobody expected to  
win and that therefore didn't get too many negative votes would win.

Juho





	
	
		
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