[EM] Generalizing "manipulability"

[Juho Laatu]

OK, Range votes are just votes. But voters
do have also opinions. They can be presented
as ratings.

If the voter casts a vote with the intention
that it reflects her opinions as accurately
as possible, then I'd call that vote sincere
(and in most cases not strategic).

If the voter casts a vote that is intended
to optimize the result of the election from
her point of view, then I'd call that vote
strategic (at least if it deviates from the
sincere opinion).

I hope we can agree on some (whatever) common
terminology that would apply to all methods.
The names of the definitions are not important
but their stability and usefulness is.

Juho



--- On Tue, 20/1/09, Abd ul-Rahman Lomax <abd at lomaxdesign.com> wrote:

> At 01:38 AM 1/18/2009, Juho Laatu wrote:
> > I don't quite see why ranking based
> > methods (Range, Approval) would not
> > follow the same principles/definitions
> > as rating based methods. The sincere
> > message of the voter was above that she
> > only slightly prefers B over A but the
> > strategic vote indicated that she finds
> > B to be maximally better than A (or
> > that in order to make B win she better
> > vote this way).
> 
> That is an *interpretation* of a Range vote. In fact, they
> are just votes, and the voter casts them according to the
> voter's understanding of what's best. This has been
> part of my point: Range votes don't "indicate"
> preference strength, as such. Consider Approval, which is a
> Range method. If the voter votes A=B>>C=D, what does
> this tell us? We can infer some preferences from it, to be
> sure, and those preferences are probably accurate, because
> Approval never rewards a truly insincere vote. But does this
> vote "indicate" that the voter has no preference
> between A and B, nor between C and D? Of course not!
> 
> Now, a Range vote. But the voter votes Approval style. What
> does this tell us about the voter preferences? *Nothing more
> and nothing less.* The voter chose to vote that way for what
> reason? We don't know!!!
> 
> They are votes, not sentiments. Voters may choose to
> express relative preference, in Range, with some fineness of
> expression, but they may also choose not to make refined
> expressions, and all these votes are sincere, i.e., they
> imply no preferences that we cannot reasonably infer from
> them with a general understanding that the voter had no
> incentive to show preferences opposite to the actual.
> 
> (Now, there is a kind of insincere voting that voters may
> engage in, but it isn't really rewarded, and voters will
> only do it when they expect it to be moot. And they may do
> this kind of insincere voting with any method whatever.)