[EM] IRV vs Plurality

[robert bristow-johnson]

On Jan 11, 2010, at 8:54 AM, Kathy Dopp wrote:

> 2010/1/10 Stéphane Rouillon <stephane.rouillon at sympatico.ca>:
>> Abd Ul,
>>
>> from the data you produce, I agree that for the Burlington  
>> election, IRV did
>> produce the same result
>> FPTP would have produced.
>
> No it did not. FPTP would have produced different voting behavior and
> elected the Condorcet winner because voters were fooled into thinking
> that IRV allowed them to vote sincerely. A Republican has not won for
> Mayor in Burlington for over a decade. Most of the people who
> preferred the Republican first would have voted for the Democrat

highly unlikely, Kathy.  in fact, certainly not the case in  
Burlington.  it would be the Progs and the Dems both wondering if  
they should vote for the other (wondering which left-leaning party is  
more established in Burlington).

the old law required 40% plurality, otherwise it goes to a runoff  
about a month later.  no one thinks, with the Dem in 3rd place with  
1st-choice votes, that the runoff would be between *any* other than  
the Prog and the GOP.  if turnout for the runoff is good, the Prog  
would win.  if turnout was poor, who knows?  i've see *two* city  
council elections go to runoff in Ward 7 and both times, the GOP  
candidate came from behind (*not* having the plurality on Election  
Day) and beat the other candidate (one time the Indie, the other time  
the Dem).  but it was with half the turnout or less.  GOPers seem to  
be more diligent in getting back to the polls on Runoff Day.


> and
> only a few hundred of those needed to do so for the Democrat to win.
>
> Plurality is far better than IRV for many many reasons including:
>
> 1. preserves the right to cast a vote that always positively affects
> the chances of winning of the candidate one votes for

and more often than not, *hurt* the credible candidate that is  
politically more aligned with the candidate one votes for.

50,000 voting for Nader elected W in 2000.  that is a matter of fact.

> 2. allows all voters the right to participate in the final counting
> round in the case of top two runoff or primary/general elections

but IRV does that in an instantaneous way UNLESS some voter changes  
their mind about their alternative candidate.  IRV or Condorcet (or  
any ranked ballot) requires the voter to choose *and* *commit* to not  
just their favorite, but their fallback candidate on the same  
Election Day.

> 3. preserves voters' right to understandably verify the election
> outcomes because the counting is simple enough for them to do,
> precinct summable

so does Condorcet.

> 4. preserves the right for local precinct control of the counts or in
> the case of election contests that cross county lines, local county
> control of the counting process

so does Condorcet.    i like precinct summable too, but it isn't the  
end-all requirement for an honest election.

> 5. is far less costly than the IRV counting process

not in Burlington.  once the infrastructure was set up (the ballot  
scanning machines didn't have to be changed at all, the difference is  
that the precinct results (that had a record for how each ballot  
looked) were transferred to city hall and a computer did the rest.   
because of FoI laws, this record is available for public scrutiny and  
has been scrutinized.

> 6. fails fewer of Arrow's fairness criteria than IRV/STV does


but it (plurality) has the worst failures.  this is what has been  
well known for decades and why election reformers sought something  
better.  IRV is sorta better but brought it's own pathologies into  
it.  Condorcet easily beats FPTP in a context where there are 3 or 4  
credible candidates.

--

r b-j                  rbj at audioimagination.com

"Imagination is more important than knowledge."