# [EM] Re: Approval STV

Chris Benham chrisbenham at bigpond.com
Fri Apr 2 16:14:03 PST 2004

```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

```