[EM] Missing the ballots' information
nkklrp at hotmail.com
Mon Aug 6 21:42:00 PDT 2001
As Demorep said, IRV fails to use most of the information in the
When working on an important project or job, would you take irrevocable
action based on only a small fraction of the available information?
That's what IRV does when it eliminates candidates based only on
looking at one rank position.
Pairwise-count methods look at every voter's every pairwise preference.
Approval, whether voting is strategic or sincere, elects a candidate who
is, overall, rated high by voters.
Both of those 2 methods do better than just looking at one rank position.
Having said something good about pairwise-count methods, I must add
the disclaimer that, under the conditions existing in actual elections,
it makes all the difference how circular ties are solved. Most
pairwise-count methods, like most rank methods in general, don't even come
to Approval's merit, in regards to the standards that are important to
most of us.
For example, the methods that measure defeats by margin-of-defeat
do quite poorly by the lesser-of-2-evils and majority-rule standards.
Simulations have shown the Margins methods doing as well as the
defeat-support methods even when there's much truncation. But those
simulations add up all the utility, including that of truncators. If
many voters are randomly chosen to truncate, then there'll by many
who fail to support a needed compromise. Their utility loss, and the
corresponding utility gain by people whose majority-defeated candidate
wins as a result, tends to obscure the difference between Margins &
defeat-support. In fact the randomness of the truncation itself
fails to bring out the differences in benefit for voters who need
a compromise and support that compromise.
For those reasons the only reasonable way to compare Margins &
defeat-support is via examples such as the ones that I posted some
time ago, for truncation and for order-reversal.
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