[EM] Dave Ketchum: IRV strategy

[Dave Ketchum]

On Dec 7, 2011, at 1:31 PM, MIKE OSSIPOFF wrote:
> Dave:
> On Dec 6, 2011, at 4:19 PM, MIKE OSSIPOFF wrote:
>>
>>
>> How to vote in IRV:
>>
>>
>>
>> When there are completely unacceptable candidates who might
>> win (I call that condition u/a, for “unacceptable/acceptable”)
>
> You replied:
>
> You DO NOT rank such since, if you rank such a candidate, so might
> enough others for this one to win - you do not want to be part of
> causing such a win.
>
> [endquote]
>
> But your vote won't reach the candidates whom you consider  
> unacceptable
> unless and until all of the acceptable candidates have been  
> eliminated.
> So, by that time, it's no longer a question of _whether_ an  
> unacceptable
> will win. It's only a question of _which_ unacceptable will win.
>
> But of course it's vastly more important to elect an acceptable vs
> determining which unacceptable wins. Still, if you have time, then
> you might as well rank the unacceptables too, so that, at least,
> the _worst_ ones won't win.
>
Voters do not necessarily agree as to which are acceptable.

If I decide, alone, what to do, then I decide based on being alone.

If a group of voters decide, each alone but thinking alike based on  
your thoughts, your words could inspire enough acting together to have  
an effect.  Inspiring this group to vote for unacceptables could cause  
such to win.
>
>>
>> IRV, like many methods, has a relatively simple strategy:
>>
>>
>>
>> Rank the acceptable candidates in order of (some guessed or
>> complicatedly-calculated measure of) their popularity.
>
> Rank in the order of what YOU see as should be most popular first.
>
>
> [endquote]
>
> Yes--You must guess which acceptable is most likely to be helped to  
> win
> by your top ranking. And then, which of the remaining acceptables is  
> most
> likely to be helped to win by your 2nd-place ranking...etc.
>
It gets tricky in IRV.

You want the proper winner to be your top rank when the counters are  
looking for what you see as proper CW.  Therefore any you rank higher  
better be read before reading this one - which is easiest if you vote  
your choice as top rank.

If you also want another as a possible winner, rank it also per the  
above paragraph - double tricky since no one can know the order the  
counters will see until the ballots have been voted.
>
>> Ideally, then rank the unacceptables in order of some
>> complicated combination of their disutility and
>> (some guessed or complicatedly-calculated measure of) their
>> popularity.
>>
>>
>>
>> Actually, ignore that last paragraph. In u/a, all the
>> unacceptables are just unacceptable. What matters is the election of
>> an
>> acceptable instead of an unacceptable.
>>
>>
>>
>> In u/a, IRV is just ranked Plurality. In Plurality you vote
>> for the acceptable candidate who is most popular (most likely to get
>> the most
>> votes).
>
> Read that carefully.  You do not vote for unacceptable here
>
> [endquote]
>
> Quite so. You never vote for an unacceptable in Plurality
>
> ...unless you're a Democrat-voting progressive  :-)
>
> But you shouldn't.
>
> Vote for the acceptable most likely to be helped to win by your vote.
> ...the acceptable most likely to be the best votegetter among the
> acceptables.
>
> Mike Ossipoff