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

[Chris Benham]

Kevin Venzke wrote:

>As for IIB, well, Top-Two Runoff already fails
>that. 
>
Technically, based on "intended rankings", I don't think it does. 
Certainly the ranked-ballot one-voting-round
automated top-two plurality runoff meets Irrelevant Ballots (IIB).  BTW, 
I gather that in the same circles where
IRV is called the Alternative Vote, that method is called the 
"Contingent Vote" (and the ghastly version of that
that allows the voter to rank a maximum of two candidates is called the 
"Supplementary Vote".)


>This method is intended to be simple yet still give good results in
>likely scenarios. It's a niche method.
>
>The basic idea is to handle at least the case that there are three viable
>candidates, with an underlying political spectrum (so that the candidates
>can be called left/right/center).
>
>So yes, the ballot is restrictive, and yes, if a fourth major candidate
>attracts votes then you will see problems. (But note that the incentives
>of the method should make a fourth viable candidate unlikely, just as
>FPP makes three unlikely.) As for IIB, well, Top-Two Runoff already fails
>that. This is just an improvement of that method.
>
In a scenario like the 2002 French Presidential election (where there 
were 12 candidates and the top 3 had
a total of  under 53% (19.83,  16.91, 16.14)  and second highest scoring 
candidate wasn't expected to be
among the top few)  I don't think the improvement would be very great.

>>>I am sure that something that uses approval ballots in the first round 
>>>could be much better. A while ago I suggested
>>>that the two qualifiers should be the  Approval winner and the 
>>>      
>>>
>>candidate 
>>    
>>
>>>with the most approval opposition to the
>>>AW. How do you see your suggested method as being better than that?
>>>      
>>>
>
>I don't think your suggestion is too bad. However, I think the strategy
>is harder for the voter to understand.
>
>Also, I think there is a strategy problem that I tried to avoid in the 
>case that your favorite candidate is left and you think he may be able 
>to defeat center head-to-head.
>
>In my method you most likely vote for left and vote against right. (Though
>if you are confident left can at least beat right, you might not do this.)
>
>In your method, if you approve both left and center, you not only can
>make center the AW, you are also unable to provide any opposition for
>left against center. You could cause the second round to be center vs.
>right. If you bullet vote for left, there is a greater chance that
>center will be shut out of the second round (which is something I, at
>least, want to try to avoid).
>

In my suggested method the voter's strategy problem is more or less the 
same as it is in plain Approval,
unless the voter is tempted by a risky Pushover strategy of trying to 
make a "turkey" the first-round AW.

I think a better method that would achieve everything you are trying to 
do with your method (technically
if not "psychologically") would be this:

"1) Voters indicate one Favourite and also Approve as many candidates as 
they like.

2) Any candidate voted as favourite on 50% or more of the ballots wins.

3) Eliminate any candidate whose max. approval opposition score is 
greater than 50%, unless that is all
the candidates.  (I'm not sure if that's possible).

4) Of the remaining candidates, the two voted as favourite on the most 
ballots go to the second round."

This uses a more expressive ballot and mainly confines the split-vote 
problem to the "top" of the ballot.
So the normal recommended strategy in the 3 viable candidates scenario 
would be vote the most preferred
of the 3 as favourite, and approve all the candidates you prefer to the 
least preferred of  the 3.

What do you think of that?

Chris Benham







>Chris,
>
>--- Forest W Simmons <fsimmons at pcc.edu> a écrit :
>  
>
>>>Kevin Venzke wrote:
>>>
>>>      
>>>
>>>>I suggest this two-round method. It's not Condorcet-efficient or even
>>>>rank ballot but I think it would be an improvement, and it's quite 
>>>>        
>>>>
>>simple:
>>    
>>
>>>>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 think this is much better as a two-round method than a one-round rank
>>>>method.
>>>>
>>>>        
>>>>
>>>I think this uses an overly restrictive ballot  and would have horrible 
>>>clone problems and fails  Independence
>>>      
>>>
>>>from Irrelevant Ballots without very good justification.
>>    
>>
>
>This method is intended to be simple yet still give good results in
>likely scenarios. It's a niche method.
>
>The basic idea is to handle at least the case that there are three viable
>candidates, with an underlying political spectrum (so that the candidates
>can be called left/right/center).
>
>So yes, the ballot is restrictive, and yes, if a fourth major candidate
>attracts votes then you will see problems. (But note that the incentives
>of the method should make a fourth viable candidate unlikely, just as
>FPP makes three unlikely.) As for IIB, well, Top-Two Runoff already fails
>  
>

>that. This is just an improvement of that method.
>
>  
>
>>>I am sure that something that uses approval ballots in the first round 
>>>could be much better. A while ago I suggested
>>>that the two qualifiers should be the  Approval winner and the 
>>>      
>>>
>>candidate 
>>    
>>
>>>with the most approval opposition to the
>>>AW. How do you see your suggested method as being better than that?
>>>      
>>>
>
>I don't think your suggestion is too bad. However, I think the strategy
>is harder for the voter to understand.
>
>Also, I think there is a strategy problem that I tried to avoid in the 
>case that your favorite candidate is left and you think he may be able 
>to defeat center head-to-head.
>
>In my method you most likely vote for left and vote against right. (Though
>if you are confident left can at least beat right, you might not do this.)
>
>In your method, if you approve both left and center, you not only can
>make center the AW, you are also unable to provide any opposition for
>left against center. You could cause the second round to be center vs.
>right. If you bullet vote for left, there is a greater chance that
>center will be shut out of the second round (which is something I, at
>least, want to try to avoid).
>
>I have a hunch that people will be more eager to "vote against" a 
>candidate they perceive to be an opponent, than to give a lower 
>preference to a candidate they may need as a compromise.
>
>Kevin Venzke
>
>
>      _____________________________________________________________________________ 
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>
>
>  
>
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