Rob Richie recently hailed the Australian house
elections (held 24 November 2007) as a
"big success" for Instant Runoff Voting (IRV).
These elections threw out both Prime Minister John W. Howard
and his party, the NatLibs, enthroning
Kevin Rudd and giving his Labor Party majority control.
But was this really a big success for IRV? We examined that using data from
Australian Electoral Commission
(Warning: All this is based on data we got from the AEC
on 30 November 2006, and it is not in final form and may
change slightly as, e.g. they count more absentee votes, recount,
etc. That will not affect our
conclusions much if at all.)
The conclusions of that examination are as follows:
If Australian house elections had been held with plain
voting rather than
then (assuming every voter would have voted for the same
candidate they top-ranked with IRV)
the results of 8 of the 150 House races would have changed.
In all 8 cases, plurality voting would have elected the NatLib candidate instead
of the Labor candidate who actually won with IRV.
More realistically, with plurality probably some third-party voters would have been more-afraid
to vote third party and would have voted for the top-two party candidates. If so, then
fewer than "8" races would alter (perhaps only 6 or 7). That would decrease the
importance of IRV in one way (fewer results changed)
but in another sense (improved voter honesty) would increase it back.
Labor and Rudd still would have won majority control with plain plurality voting, just
a smaller majority (77 out of 150 seats, versus what they got with IRV, which was 85 out of 150).
In view of this, we agree with Rob Richie that these elections were a "big success,"
or at least a "success,"
But approval and range voting would have been an even bigger success as we'll
If Australia had employed
voting instead of IRV, then we believe the same result would have happened,
i.e. exactly the same 8 races
would have swung toward Labor. (Perhaps only 6 or 7 with range and approval if
the third-party voters did not approve Labor enough or score it highly enough, but if so
then range & approval would arguably have made a better call than IRV.)
All 8 IRV-swinging races displayed a pathology called "participation failure"
or "no-show paradox." That is, in every case, adding some number of extra
Green>Labor>NatLib voters, would have caused the IRV winner to become NatLib.
That is bad, because:
These extra voters, by voting honestly, would have made the election result worse in their view.
They would have been better off not voting at all (as, in fact, they didn't).
They also would have been better off voting dishonestly; and with these extra Green voters,
some of the Labor voters also would have been better off voting dishonestly.
All 8 losing Natlib candidates have the following valid gripe,
enabling them to attack the legitimacy of IRV:
I lost to Labor with IRV,
But if extra voters, all of whom ranked me dead last and preferred Labor over me,
entered the picture, then I would have won,
So, since I would have won and
defeated Labor even with this handicap, why the heck did I lose without the handicap?
My defeat was bogus or the election system (IRV) is bogus, or both.
Approval and Range did not exhibit any such pathology, hence no candidate in
any of the 150
races would have had any such
valid gripe enabling attacking the legitimacy of
range & approval voting.
The myth that IRV pathologies are "extremely rare" is totally refuted.
The claim that IRV improved on plain plurality voting is undermined because
the two systems delivered exactly the same winners in every case, except for
cases in which the legitimacy of IRV can validly be questioned.
Voters might have wanted to get rid of Howard and install Rudd because they disliked
the Iraq War. That's fine, but maybe they did not like the pill they then were forced to swallow
of implicitly endorsing Rudd's semi-Socialist economic views.
The difficulty here for such a voter is that since IRV leads to 2-party-domination
(Australia's 2007 House contains zero third-party members) she has no choice
besides Rudd & Howard. If Australia had a voting system that did not lead
to 2-party domination, she could have more credible choices – e.g. perhaps there would
be an antiwar and anti-Socialist choice. That's an advantage for approval
and especially range voting, versus IRV.
Australia is still counting and recounting all the close IRV elections 1 week later and
warn that it is not clear that Labor really has 85 seats, etc (those results are subject to
change). That is because
IRV is a difficult system to count, and ties and near-ties even between "no hoper"
candidates, can change the winner.
of invalid "spoiled" ballots
were easily sufficient to change the winner in many of the 150 races.
(And, incidentally, spoilage rates are
lower with range and approval voting.)
Approval (or even range) voting are simpler to count and less subject to tie-crises.
They would have been counted sooner with fewer worries, less effort, and less cost.