[EM] Social utility is more important than median utility

[MIKE OSSIPOFF]

Jobst--

You wrote:

>The median is a simpler, more accurate, and more robust measure of
>social utility than the sum!

I reply:

Probably so.

You continued:

>It has the additional advantage that we
>need not assume that utilities possess an additive scale.

True, but there's a good reason for judging a method by the sum of the 
utilities by which all the voters rate the winner:

We discuss voting systems in the hope that one of the better ones will be 
enacted and used in some future elections.

Maybe you or I will be one of those voters at that time, or maybe it will be 
a relative or descendant or ours.

We don't know what kind of examples those future elections will be like, or 
which voters in those examples we or our descendants or relatives will be.

But we maximize our utility expectation, or that of our descendants or 
relatives, in that future election if we advocate a voting system that does 
very well by social utility, the sum of the voters' utilities.

That's a good reason to judge methods by SU, and I claim that it's 
completely compellling.

By the way, in Merrill's simulations, Approval did significantly better than 
IRV.

If distances in issue-space are measured by city-block distance, then the CW 
always maximizes SU in spatial models.

If distance in issue-space is measured by Euclidean distance, then the CW 
maximizes SU under the conditions assumed in all spatial simulations.

If, for any line through come central point in issue space, the voter 
population density distribution is the same in both directions along that 
line from the central point, then, even with Euclidean distance, the CW 
maximizes SU.

The condition in the above paragraph is met, for instance, if the voters are 
normally distributed about a central point in each issue dimension, as is 
routinely assumed in spatial model simulations.

Mike Ossipoff

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