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

[Warren Smith]

>It seems to me that approval and range voting eliminate most of the
strategic opportunity in single winner elections and the marginal
improvement of other methods is fairly small. Can anyone point me to
analysis, preferably at a layman level, that contradicts or supports this
assertion?
>Or, in succinct terms, what are the strategic flaws in approval or range
voting?
>Thanks, Matthew Welland

--well... there is the whole rangevoting.org website...
my more-recent papers at
math.temple.edu/~wds/homepage/works.html
discuss range voting including some ways it is provably better than every
rank-order voting system for either honest or strategic voters...

--but those are not exactly "succinct"...

OK Let me try:
1. Range for 100% honest voters behaves better than IRV, Borda,
Condorcet and it is pretty intuitively clear why -- strength of
preference info used, not discarded.

2. For 100% strategic voters Borda is a total disaster as is also
pretty obvious... far worse than approval voting...  but range voting
just degenerates basically to approval voting, which still works
pretty well since, e.g. it obeys the "favorite betrayal criterion."
If the strategic voters use "I'll exaggerate on the top two" naive
strategy (which in fact, in the real world, they pretty much do) then
Condorcet and IRV both degenerate
to strategic plurality voting, which is pretty obviously worse than
approval voting,
so range beats them.  For Condorcet systems with ranking-equalities allowed,
they might behave better with strategic voters, though.  I've posted
on that topic before.

3. The main perceived flaw in range voting is for strategic+honest
voter MIXTURES
and under the worrying assumption that who decides to be strategic, is
CORRELATED with the politics of that voter.  Thus for example,
strategic Bush voters could beat unstrategic Gore voters.  Problem
isn't really much of a problem if the Bush strategy-fraction is the
same as the Gore strategy fraction (a claim backed up by computer
sims). It is only if they differ.

4. I'm unaware of any evidence from the real world that Bushy and
Gorey voters really are any different strategically with range voting.
   However, there is evidence that
Nader voters are less strategic and more honest.  (Not surprisingly
since voting Nader
in the USA *was* unstrategic.)   However, the evidence from the real
world is that all political types of range voters are substantially
honest, i.e.only a small fraction vote approval-style, and this causes
Nader, despite this relative disadvantage, to do a lot better with
range voting than he does with approval voting.


-- 
Warren D. Smith
http://RangeVoting.org  <-- add your endorsement (by clicking
"endorse" as 1st step)
and
math.temple.edu/~wds/homepage/works.html