[EM] IMHO, IRV superior to approval

[Stephane Rouillon]

Above all, I agree there are some differences between "equal power to voters" and

"1-person 1-vote". I agree too that "1-person 1-vote" is a fuzzy concept hard to
generalize
to electoral methods other than FPTP.

Now, I partially disagree with Adams in his analysis. But maybe it's my
understanding which is erroneous...
Let me precise:

Adam Tarr a écrit :

> Stephane Rouillon wrote:
>
> >I  read Olli's mail last time but I am sorry that I have to disagree with
> >Adam.
> >
> >Olli showed that putting some restrictions (by the mistress)
>
> What restrictions?  Olli's approach uses regular approval ballots.  You
> don't need any input from the voters after you collect the ballots.  The
> talk about lining up and counting heads was just for illustrative purposes.
>
> >  allows to obtain an equivalent to approval that is conducted as several
> > FPTP rounds. However, these restrictions muzzle some voters at some
> > rounds (read well Adam, some of those kids have to gang behind one of the
> > contestant, they cannot chose).
>
> Your choices are uniquely determined by your ballot, just as in IRV.  You
> vote for a candidate (line up behind them) if you approve that candidate
> and not the other.

I do agree but the instant in which you fill your ballot makes all the
difference.
I can agree with you when comparing approval and IRV when IRV voters fill only
once their ballot
at start. In that case, one can define "1-p 1-v" thus both verify or not the
criteria.
with n candidates, It does not stop voters using approval to express a difference
in only
approved x (n-approved) possible pairwise contests while the same voters would
participate to all
possible pairwise contests. This leads me to conclude IRV is superior to
approval.
I leave to arguers the fact that participating to every pairwise contest is or
not a condition met by
"1-person 1-vote".

> >Clearly, during these steps, the process gives a choice to some voters,
> >not to others.
>
> The same is true in IRV.  Consider this equivalent definition of IRV:
>
> "In each round, if there is not a majority first place candidate, then
> compare the two candidates with the fewest first place votes.  The one with
> the least first place votes is eliminated."

These versions are not totally equivalent in my eye if you consider using the
precedent round
as an information input to guide your next round rankings. As Mike Ossipoff would
say,
the level of information can affect -wise and unwise- unsincere rankings.

A round version of IRV (run-off IRV) is used too in pratice. Olli's round version
of
approval seemed to tie voters to their initial preferences. If you do not, I
think you obtain IRV
sequential version...

> In IRV, I only vote on which candidate is eliminated if the top remaining
> choice on my ballot is one of the candidates near elimination.

...knowing who is left.

>  In
> Approval, I only vote between two candidates if I approve one and not the
> other.

I assumed it was the approved initial set. After some rounds, me for example
would want to
get more specific...

> Now, let's compare the "sequential" approach to approval with this approach
> to IRV.  Both will always produce exactly the same winner as they would in
> normal approval and IRV.
>
> In both cases, we pick two candidates out using the same approach.  We then
> look at everyone's ballots, divide the voters into A's supporters, B's
> supporters, and abstentions based on the information on the ballots.  The
> method we use to make these distinctions is different, but that is
> irrelevant to the 1P-1V question since both approaches split the electorate
> into these three groups.  We then eliminate the candidate with fewer votes,
> and move on.  Again, it's the same.
>
> I cannot see any reason why one would be considered compliant with 1P-1V
> and the other would not.  There is no reason.
>
> >In my humble opinion, Olli showed with a great thoroughness (spelling?) that
> >approval is not "one person one vote" at every round, thus at a whole.
>
> By your definition, IRV would not be 1P-1V either.

I agree with you. The IRV (one ballot version) would not. The IRV run-off version
when
you ask back voters their choice at every round would. But again you are right
saying
"1-p 1-v" can be defined many ways.

>  After all, just as in
> approval, there are voters who fail to cast a vote in certain rounds.  And
> I haven't even mentioned exhausted ballots yet.
>
> Quite simply, there is no way to define 1P-1V on the overall election
> method (a function from voted ballots to a winning candidate) such that IRV
> passes and Approval fails.

Depends of the IRV version, but I may be wrong.

>  There are many ways one can count ballots and
> get the same results, and I can always choose a pair of approaches for IRV
> and approval where they either both pass or both fail 1P-1V, depending on
> how you define it.
>
> -Adam
>
> ----
> Election-methods mailing list - see http://electorama.com/em for list info

It may not fit "1-person 1-vote", but clearly IRV lets all voters express a
preference at the last round in the sequential version,
while approval restricts that "right or opportunity" to voters who placed their
approval cut-off between the last two contenders.
You can say that the exclusion is random and thus it meets even "equal power to
voters", or better "equal esperance (in the
mathematical sens) to voters", but it is a symptom of a less effective selection
process, and thus a less effective electoral method to me.
If we assume a voter is "right" 51% of the time, using a random set of 90% of the
voters can only diminish the probability to select the best option.

Please convince me, I always try to see things differently.
Steph