[EM] Testing 1 2 3

Bart Ingles bartman at netgate.net
Fri Jan 2 15:07:03 PST 2004

Dgamble997 at aol.com wrote:
> Bart Ingles wrote:
> >There is no way to accurately determine approval voting results using
> >this input format. About the best you can do is to assume that for
> the
> >A>B voters, half approve both A and B, and the other half approve
> only
> >A. This would make approval voting equivalent to Borda, at least
> where
> >fully ranked ballots are concerned.
> The model assumes that voters either use a good Approval strategy (Rob
> Le Grand's strategy A) or approve all candidates they rank. The
> proportion of voters using strategic voting and non-strategic voting
> can be varied.

Good strategy requires either cardinal utilities or strategic info, or
preferably both.  Although I suppose you could assume pure strategy if
you also assume that each voter knows how all the other will vote.  In
that case approval should be essentially equivalent to Condorcet.

The second option, that the voters only rank candidates they would
approve, will alter the results for all of the ranked ballot methods. 
Maybe you could include a special "none of the below" candidate, to mark
the approval cutoff for various blocs of voters.

> >Also, I notice that you allow equal last-choice preferences (e.g.
> >A>B=C), but not equal first preferences (A=B>C). Doing one but not
> the
> >other would bias the results. But then the only reasonable way to
> >handle (A=B>C) for IRV or Plurality would be to assume that half vote
> >one way, and half the other.
> This is not correct. The model allows truncation but not equal
> preference.

But truncation is equivalent to equal last-choice preference for all of
the methods listed below.

> A>B means voters rank A first and B second and C not at
> all.

How is this different from ranking C last?  In other words, how is A>B
different from A>B>C?

> In strategic voting whether A>B voters approve A or A and B
> depends on how the voters respond to the information in an opinion
> poll using strategy A. In non-strategic voting the voters approve all
> candidates they like and hence A>B voters approve both A and B.

Again, this last assumption either invalidates the approval results or
the ranked ballot results (or both).  If you assume that the voters
truncate all preferences that they wouldn't approve of under approval
voting, then you are altering the ranked system results.  If, on the
other hand, you assume that the voters only truncate when they sincerely
don't have a preference between the truncated candidates, then your
approval results are invalid.


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