[EM] Why Not Condorcet?

[Dave Ketchum]

On May 17, 2010, at 11:28 AM, Abd ul-Rahman Lomax wrote:
> At 10:12 PM 5/16/2010, Dave Ketchum wrote:
>> On May 16, 2010, at 6:11 PM, Abd ul-Rahman Lomax wrote:
>>> At 02:16 PM 5/16/2010, Dave Ketchum wrote:
>>>> On May 16, 2010, at 9:24 AM, Abd ul-Rahman Lomax wrote:
>>>>> At 06:34 PM 5/15/2010, Dave Ketchum wrote:
>>>>>>> Some objections to Condorcet could be:
>>>>>>> 1. It is not expressive enough (compared to ratings)
>>>>>> Truly less expressive in some ways than ratings.
>>>>>>   This is balanced by not demanding ratings details.
>>>>>>   And more expressive by measuring differences between each pair
>>>>>> of candidates.

I had written promoting Condorcet.

Kevin Venzke offered some objections, #1 is above, indicating that  
ratings have the value of being more expressive.  I responded to his  
thoughts, also above.

Abd ul, who often writes usefully, wrote a book here, wandering into  
various topics such as Bucklin.
>
>>
>> The base topic is Condorcet.  It would take a book to respond to all
>> your extensions such as IRV.  Likewise I see no benefit in adding
>> Borda - Range/score is an adequate source for ratings.

 From Wikipedia:
Condorcet:  For each ballot, compare the ranking of each candidate on  
the ballot to every other candidate, one pair at a time (pairwise),  
and tally a "win" for the higher-ranked candidate.

Range voting uses a ratings ballot; that is, each voter rates each  
candidate with a number within a specified range, such as 0 to 99 or 1  
to 5.
>>
In Condorcet the counting is of pairs of candidates so the  
possibilities for A vs B cannot be other than A>B , A=B, or A<B - no  
way to have a skipped rank.

In Range the limits can be other than 0-99, but those are suitable for  
the discussion.
>
> Dave, you apparently don't understand a good deal of what you read.  
> That's okay, take your time.
>
> My point was about your use of "demanding ratings details," which is  
> not intrinsic to range methods. In particular, I've been pointing  
> out, Borda is a ranked method that is a Range method, and it becomes  
> full range if the method simply allows one to equal rank any two (or  
> more) candidates without disturbing the points given to other  
> candidates.

The topic is "ratings" and, Range being adequate for the cause, there  
is no need to wander into other methods.
>
>>  I used care in
>> mentioning ranking to avoid complications such as you add - and
>> clearly included equal ratings and rankings.  Your extensions could  
>> be
>> useful if they contributed value, but not if they just complicate.
>>>>>
>>>> Assuming I LIKE A, B & C are almost as good, and I DISlike D:
>>>>
>>>> I can rate A=99, B=98, C=98, D=0 or rank A high, B&C each medium,  
>>>> and
>>>> D low (A>B=C>D).
>>>
>> In ranking all I can say is to rank B&C above D and below A..
>>
>> Go back to the example and see B and C each rated 98 because I DO NOT
>> want them to lose to D.
>
>>>> The example ratings of A, B,&C do the most I can to make any of  
>>>> them
>>>> win over D; the example rankings do the most I can to make A win, D
>>>> lose, and give B&C an equal chance.
>>>>
>>>> In Condorcet I ranked A over B and C over D but could not express  
>>>> the
>>>> magnitude of these differences.  In Score I must rate with numeric
>>>> values that include the differences.
>
> You are showing, Dave, that you have completely missed the point.  
> Again, you use "must." No, a Range ballot can simply be a list of  
> ranks.

Such a list might be - but numbers would make more sense with limits  
such as 99.