Re: [rtcweb] Voting method choice (Re: Proposed Video Selection Process)

[Harald Alvestrand <[e-mail]>]

On 11/21/2013 08:11 PM, Harald Alvestrand wrote:
> Forking this thread, and leaving aside all consideration of whether 
> the IETF should do voting, whether the electorate is the right 
> electorate for the decision and so on:
>
> I wonder if Instant Runoff is the right choice for this situation.
> Instant Runoff means that when you don't get a majority for anything, 
> you drop the lowest-ranked candidate and distribute the ballots that 
> had this as their #1 across the other candidates.
>
> This has the property that in a polarized situation, compromises may 
> get dropped out of the running before the alternatives that they might 
> serve as a compromise between.
>
> In this case, I'd favour a Condorcet-compatible method, such as 
> Schulze; it provides the guarantee that if a choice is preferred by a 
> majority of the participants over every other choice, it will always 
> be chosen.
>
> http://en.wikipedia.org/wiki/Condorcet_method#Schulze_method

I haven't seen much response to this - except pointing out that no 
voting method is perfect - but I really think the issue of Condorcet vs 
IRV matters in this case.

We have two strong camps who have a clear preferred choice, and we have 
some possible compromises. Me being the compromising type, I think we 
might be better off with a compromise than one of the strong camps' 
preferences.

Let's imagine, for a moment, that the options are:

A: Codec A
B: Codec B
C: At least one of Codec A and B

If the distribution is like this:

A proponents (40%): A C B
B proponents (40%): B C A
Compromisers group 1 (5%): C A B
Compromisers group 2 (15%): C B A

Then under IRV, the first round will go 40/40/20, alternative C will be 
eliminated, and B will be chosen.
Under Condorcet, the outcomes will be:

- A outranks B on 55%
- C outranks A on 60%
- C outranks B on 60%

Therefore, C is a Condorcet winner.

IRV is less likely to lead to a second-ranked compromise that everyone 
can live with than Condorcet.