HUH!!! How did we get here, where the topic is IRV???
Plurality with runoff: If Plurality fails to produce a winner. then
the leading candidates - usually two - are voted on in a separate
election.
Exhaustive Ballot: If Plurality fails to produce a winner, then the
candidate with the fewest votes is eliminated and a further round of
voting occurs. This process is repeated for as many rounds as
necessary until one candidate has a majority. NOT GOOD to risk having
many such rounds in a public election with thousands of voters.
IRV (Instant Runoff Voting): Can be thought of as a descendant of
either of the above, with the voter permitted to rank multiple
candidates on a single ballot and the counters to consider only the
top ranked in each round. If Plurality fails to produce a winner,
then the candidate with the fewest votes is eliminated from all
ballots, all thus exhausted ballots discarded, and a further round of
counting occurs. This process is repeated for as many rounds as
necessary until one candidate has a majority.
I have not done LNH analysis.
On Sun, 27 Jul 2008 00:06:51 +0100 James Gilmour wrote:
Kathy Dopp > Sent: Saturday, June 21, 2008 5:20 AM
"Later-No-Harm", however, is incompatible with the basic
principles of majority rule, which requires compromise if
decisions are to be made. That's because the peculiar design
of sequential elimination guarantees -- if a majority is not
required -- that a lower preference cannot harm a higher
preference, because the lower preferences are only considered
if a higher one is eliminated.
The meaning of the second sentence isn't completely clear to me, but I am
fairly sure there is a perverse interpretation of
"majority" in the first sentence. An IRV election is an Exhaustive Ballot
election contracted into one voting event, instead of
being spread over several rounds in which the one candidate with fewest votes
is eliminated at each round. It is no surprise that
the numbers of voters participating varies from round to round - usually a
progressive (or severe) decline. The votes in an
IRV election might look like this:
>
> Round 1
> A 4,000
> B 3,000
C>A 400
C>B 1,400
C 200
D>B 100
D 900
> Total voting 10,000
>
> Round 2
A 4,000
B 3,100
C>A 400
C>B 1,400
C 200
Total voting 9,100
>
> Round 3
A 4,400
B 4,500
Total voting 8,900.
>
B is the majority winner in Round 3, that is to say, the majority
winner of those voters then voting.
DWK
Exhaustive Ballot election might look like this:
Round 1
A 4,000
B 3,000
C 2,000
D 1,000
Total voting 10,000
Round 2
A 3,500
B 2,500
C 1,500
Total voting 7,500
Round 3
A 3,000
B 2,000
Total voting 5,000.
A is the majority winner in Round 3, that is to say, the majority winner of
those voters then voting. And IRV satisfies that
criterion - and the Exhaustive Ballot is the valid comparison for IRV
(because that is the origin of IRV). The only difference is
that to ensure the integrity of the count (accounting for all ballot papers at
all stages of the count), the ballot papers (votes)
of those who opt out at the later stages (rounds) are recorded as
"non-transferable".
But many think that
later-no-harm is undesirable
"Many" on this list may think that, but it is my experience of more than 45
years as a practical reformer explaining voting systems
to real electors, that 'later no harm' does matter greatly to ordinary
electors. If they think the voting system will not comply
with 'later no harm', their immediate reaction is to say "I'm not going to mark
a second or any further preference because that will
hurt my first choice candidate - the one I most want to see elected." And of
course, if you once depart from 'later no harm' you
open the way to all sorts of strategic voting that just cannot work in a 'later
no harm' IRV (or STV) public election with large
numbers of voters.
But many think that
later-no-harm is undesirable because it interferes with the
process of equitable compromise that is essential to the
social cooperation that voting is supposed to facilitate. If
I am negotiating with my neighbor, and his preferred option
differs from mine, if I reveal that some compromise option is
acceptable to me, before I'm certain that my favorite won't
be chosen, then I may "harm" the chance of my favorite being
chosen. If the method my neighbor and I used to help us make
the decision *requires* later-no-harm, it will interfere with
the negotiation process, make it more difficult to find
mutually acceptable solutions.
This is all irrelevant because in a public election there is no negotiation
between voter and voter or between voter and candidate.
I know that there are proposal for voting system that would incorporate
"negotiation" of various kinds, but none of those was under
discussion here.
James Gilmour
--
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Dave Ketchum 108 Halstead Ave, Owego, NY 13827-1708 607-687-5026
Do to no one what you would not want done to you.
If you want peace, work for justice.
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