[EM] Re: Approval STV

[Chris Benham]

Kevin,
You  wrote  (Wed.Mar.31):

>A method I would rank between Condorcet and Approval is AER, or "Approval STV."
>It's IRV, but the elimination order is based on approval.  Because the approval
>counts don't change, and the elimination order is thus fixed from the beginning,
>it's monotonic.  It's intuitive, and gives similar results to WV methods.
>
To avoid the need for  approval cutoffs, why not use the  plain 
 Weighted Mean Approval scores to set the 
fixed elimination schedule, and then the rest is like fractional  IRV 
with a majority stopping rule ?

Weighted Mean Approval .
Voters rank the candidates, equal preferences ok.
Each candidate is given a weight  of  1  for each ballot on which that 
candidate is ranked  alone in first place,  1/2  for each ballot  on 
which that candidate is equal ranked  first with one other candidate, 
1/3 for each ballot on which that candidate is ranked equal first with 
two other candidates, and so on so that the  total of  all  the weights 
equals  the number of ballots.
Then  approval scores  for each candidate is  derived  thus: each ballot 
approves all candidates that are ranked in first or equal  first place
(and does not approve all candidates that are ranked last or equal 
last). Subject to that, if the total weight of the approved candidates 
is less than half  the total of number of ballots, then the candidate/s 
on the second preference-level are also approved, and the third, and so 
on; stopping as soon as  the  total weight of the approved candidates 
equals or exceeds half the total mumber of ballots.

Chris Benham