[EM] polls and manipulation

[Juho Laatu]

I assumed that the poll is just some regular
poll before the election. The final votes will
most probably be different, but probably not
too much different.

I agree that the results of polls may be all
over the map. That may be because of changes
in the opinions, changes in the way the questions
are presented, too small sample size etc. It
is also possible to publish strategic polls (with
biased/falsified information) with the intention
to influence the opinions, or the strategies that
others will use. And it is possible to refer to
those polls that one wants.

The fact that polls are inaccurate, conflicting,
and can not fully predict the opinions on the
election day has also an impact on the strategic
opportunities. Strategies that require detailed
knowledge of the opinions (and maybe also good
central control of the strategic voters) and that
may backfire are often too difficult to handle in
real life elections. Many Condorcet examples /
strategic opportunities fall in this category.
Also many IRV strategies may fall in this category.

For these reasons I like the idea of presenting the
strategic cases as example cases from real life
(not as theoretical extreme cases on paper, or only
as theoretical on/off criteria without considering
their negative impact and probability of success in
real life elections). Of course strategies will
also always be based on (inaccurate) polls, not e.g.
on exact knowledge on the ballots and ability to
change those ballots that one wants, and to keep
other ballots unchanged.

The inaccuracy of polls is thus often a positive
thing since it makes successful implementation of
strategies in may cases impractical.

Juho


--- On Sat, 22/11/08, Jonathan Lundell <jlundell at pobox.com> wrote:

> From: Jonathan Lundell <jlundell at pobox.com>
> Subject: polls and manipulation
> To: juho4880 at yahoo.co.uk
> Cc: election-methods at lists.electorama.com, "Greg" <greg at somervilleirv.org>
> Date: Saturday, 22 November, 2008, 8:01 PM
> On Nov 21, 2008, at 11:00 PM, Juho Laatu wrote:
> 
> > Here's one IRV example with three strong
> candidates and where voters do have some incentive to
> compromise.
> > 
> > 45: A>B>C
> > 10: B>A>C
> > 15: B>C>A
> > 30: C>B>A
> > 
> > We have one centrist candidate (B) between two others.
> > 
> > According to this poll it seems that B will be
> eliminated first, and then A would win since some B
> supporters prefer A to C.
> 
> And where is this poll coming from? Even in an election
> that's polled obsessively, with only two viable
> candidates, the poll results are all over the map:
> http://www.pollster.com/blogs/pollster_accuracy_and_the_nati.php
> 
> We see popular-vote polling predicting Obama's margin
> as anything from +2 to +11.
> 
> Vincent Conitzer and others have been doing some
> interesting work on how easy/difficult it is to manipulate
> an election by changing votes. An interesting corollary
> question is: how much information does a manipulator need
> about the election profile in order to have a decent chance
> of success?
> 
> One can imagine circumstances in which manipulation is easy
> (for Nader supporters in Florida 2000, say), but, intuitive
> or not, how is a voter going to have the kind of information
> (and confidence in it) to successfully manipulate the above
> example. Not to mention the recursive tangle we get into if
> we assume that *all* the voters share this information...