[Election-Methods] YN model - simple voting model in which range optimal, others not

[Dave Ketchum]

On  Thu, 27 Mar 2008 22:12:45 -0400 Abd ul-Rahman Lomax wrote:
> At 12:17 PM 3/27/2008, Dave Ketchum wrote:
> 
>> Ok, I give up on poking at this one.
>>
>> While the stated votes may be possible, I do not accept them as being of
>> enough expectability to be useful in comparison among the election 
>> systems.
> 
> 
> Dave, you've been reading the Election Methods list for quite some time. 
> Election methods are compared on a theoretical basis, all the time, 
> based on constructed scenarios that show *possible* behavior. For an 
> example, it's commonly asserted that Approval Voting fails the Majority 
> Criterion. Why? Well, it is possible that one candidate gets a majority 
> and does not win, because another candidate gets a *larger* majority.
> 
> Now, how likely is this? Consider a two-party system. It is, by 
> definition, rare that the winner isn't from one of the two major 
> parties. Approval Voting would be introduced into this context because 
> it can allow voters who support a third party candidate to vote, as 
> well, for a major candidate and thus not waste their vote, reducing the 
> "spoiler effect," and possibly vote-splitting effects.
> 
> In this context, how likely is it that two candidates gain a majority. 
> Imagine that the electorate is, say, 45% D, 45% R, and 10% G. That's a 
> large third party.  For two candidates to gain a majority, almost 
> certainly what we'd have to see is a significant number voters voting 
> for both the R and the D. Sure, it will happen, but because there will 
> also be a significant number of G voters who don't vote for either an A 
> or a B, it's quite unlikely that two candidates will gain a majority, 
> and, indeed, it remains quite possible that no candidate will. No voting 
> method can guarantee a majority winner except by forcing voters to make 
> a choice, say on a ranked ballot, as in Australia, where full ranking is 
> required.
> 
> It was not claimed that this would be a common scenario, only that it 
> was possible, just as it is possible to have more than one candidate 
> gain a majority in Approval, and it is possible for 2/3 of voters to 
> vote *against* a candidate and that candidate wins under IRV. These 
> studies show something about the possible behavior of election systems, 
> and, in fact, Plurality is known to be ridiculously bad; but that is 
> only under relatively rare conditions, in *most* elections plurality 
> works well enough, producing the same result as, say, IRV or other more 
> advanced methods would. It's the exceptions, though, that are worrisome.
> 
Certainly ugly scenarios are appropriate for warning users as to what is 
stupid and such as warning users about traps a method is subject to.

YN is made to appear as a comparison of methods, whereas it is tailored to 
make Range look good.

What was done in YN with Plurality illustrates this.  We call Plurality an 
unacceptable method because of what happens when voters WANT to approve 
more than one candidate but, within its abilities, it is properly neutral.

For the type of Plurality demonstration desired here a biased collection 
of voters was created.
-- 
  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
            Do to no one what you would not want done to you.
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