[EM] Margins vs. Winning Votes

[Juho Laatu]

On Jul 26, 2005, at 23:41, Dave Ketchum wrote:

...
> My comparison of methods:

Nice description of strategies and summary of methods, thanks.

>      Condorcet margins - like above, but less apt to pick best liked.

Why less apt? I find the choices of margins quite ok.

>      Approval - its backers like to brag, but it is not that simple - 
> unlike Condorcet and IRV, voters CANNOT say:  I prefer Nader but, only 
> if I cannot have Nader, give me Kerry as better than Bush.
>      Ratings - I choke on the complexity as worse than the above.

I think there is a trade-off between expressiveness and strategies. 
Rating based methods are nice since they can express so much, but they 
are too vulnerable to strategies and therefore unusable in most 
(contentious) elections. Approval, as you note, lacks expressiveness. 
But strategies are not that big of a problem. Pair-wise methods and IRV 
are somewhere in between when it comes to expressiveness. Pair-wise 
methods are more expressive than IRV. I hope their problems with 
strategies are not too bad and their expressiveness could be used in 
elections for the benefit of all.

> I do not see how this example promotes margins:
>      Under wv the plotters achieved their goals.  NOT that I approve, 
> for they were only guessing as to what other voters might do.
>      Under margins they claimed to prefer the LEAST liked candidate 
> over one they actually preferred.  Fact that their strategy elected 
> the least liked is not a success to celebrate - more a warning to be 
> cautious when considering strategy.

The reason why I think the example speaks in favour of margins is that 
the results of the strategy brought no benefits to the strategic voters 
(who seemed to try some sort of a burial strategy but were mistaken and 
failed). Therefore margins (at least in this case) encourage people to 
simply vote sincerely and forget strategies. (while winning votes 
encouraged plotters to vote strategically and also gave results to 
them)

BR,
Juho