matt welland wrote:
On Sat, 2011-11-26 at 22:31 -0500, robert bristow-johnson wrote:
On 11/26/11 6:58 PM, matt welland wrote:
Also, do folks generally see approval as better than or worse than IRV?
they don't know anything about Approval (or Score or Borda or Bucklin or
Condorcet) despite some effort by me to illustrate it regarding the
state senate race in our county.
I wasn't clear. I want to hear opinions from the list: Is approval
better or worse than IRV and why?
In my opinion, Approval is somewhere between IRV and "the advanced
methods" (good Condorcet methods, MJ, etc).
The reason I think Approval is better than IRV is that while IRV makes
its own decision about essentially whether to emulate people voting both
Nader and Gore, or Nader alone, Approval lets the voters decide on their
own. The voters can therefore approve both if it's more important to
beat Bush than to support Nader over Gore, or approve Nader only if
Nader's got a chance.
The reason I think the advanced methods are better than Approval is that
they take this burden off the voters when the voters are sincere. If you
vote Nader > Gore > Bush in Schulze (say), then you're both helping
Nader to win against (Gore, Bush) and Gore to win against Bush. If Gore
is a CW with a sufficient margin that you don't create a cycle - well,
then Gore wins. Same with Nader.
If there's a cycle, it gets a bit more tricky. The method is easier
influenced by strategy and your vote could hurt you. The Condorcet
criterion no longer says what the answer should be, and the method thus
has to use more indirect reasoning to find out who should win.
At least it narrows down the region in which strange things can happen.
The good Condorcet methods pass criteria like Smith and independence of
Smith-dominated alternatives, and so further narrow down these regions.
So, in short: IRV makes a guess as to which comparisons are the most
important (using the logic of "least first-place votes = worst"), and
when it gets it wrong, there's your center squeeze. Approval gives the
decision to the voters, who will do better if they have access to
polling data. Condorcet looks at more comparisons at once, while MJ
reads ratings using robust statistics to satisfy criteria like Majority
and to deter strategy.
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