[EM] Anyone got a good analysis on limitations of approval andrange voting?

[Raph Frank]

On Sun, Nov 8, 2009 at 5:22 PM, Terry Bouricius
<terryb at burlingtontelecom.net> wrote:
> A somewhat more accessible (and available online for free) analysis of
> strategic vulnerability of various methods is in this doctoral paper by
> James Green-Armytage ("Strategic voting and Strategic Nomination:
> Comparing seven election methods"). He found that Range and Approval were
> just about the worst in terms of manipulability.
> http://econ.ucsb.edu/graduate/PhDResearch/electionstrategy10b.pdf

His assumptions about how people vote are not very realistic.

Plurality -> vote for favourite

Top 2 - run-off -> vote for favourite and then best of top 2
Alternative vote -> honest ranking
Minimax -> honest ranking
Borda -> honest ranking

Approval -> vote for better than mean
Range -> give max to favourite and min to least favourite and scale the rest

His analysis is pretty interesting and he has created a condition for
each method that is needed for the winner to be vulnerable to loss if
a group of voters switched their vote.

In practice, people are able to handle the basics of plurality strategy.

It would be interesting to see how approval scores with a pre-election
poll being performed.  For example, each voter approves based on a
mean threshold and then use the result of that election to work out
the top-2.