[EM] Condorcet-Approval hybrid method

[Daniel Bishop]

Russ Paielli wrote:

> Forest Simmons simmonfo-at-up.edu |EMlist| wrote:
>
>> Russ asked about what we used to call "Approval Completed Condorcet."
>>
>> The legendary Demorep was an avid proponent of several variations of 
>> this idea, one of which he christened ACMA for Approval, Condorcet, 
>> Maximum Approval, a three step method:
>>
>> Step 1: Approval: first eliminate all candidates with more 
>> disapproval than approval.
>>
>> Step 2: Condorcet: elect the Condorcet Winner among the remaining 
>> candidates if there is one.
>>
>> Step 3: Maximum Approval: in the case of no CW in step 2, elect the 
>> candidate with maximum approval.
>
>
> The first step is arbitrary and I would eliminate it.
>
> I would start by simply choosing the CW if one exists, or paring the 
> field down to the Smith set otherwise. Then I would eliminate the 
> candidate with the lowest approval and repeat.
>
> I thought of this yesterday while I was working out, and I thought I 
> had come up with something big. Then I searched the EM archives and 
> discovered that Kevin Venzke had mentioned it way back in 2003.
>
> Oh, by the way, I would *not* allow equal rankings. Why not? I just 
> don't like them.

Not a very convincing reason to me.

> They strike me as an unnecessary complication

How are they a complication?  If anything, equal rankings make it 
*easier* to construct a pairwise matrix.

> and little more than a way to game the system.

There's a potentially important practical advantage, in that it allows 
voters to cast a Cardinal Rankings-style ballot.  For example, you could 
let:

Rank 1 = ideal candidate
Rank 2 = candidate I have minor disagreements with
Rank 3 = candidate I have major disagreements with
Rank 4 = candidate I wouldn't vote for even if he were running against 
Hitler and Stalin

If there are a large number of candidates, this could be considerably 
easier for the voter than casting a fully-ranked ballot.