[EM] Less-skilled voters under Approval?

[John B. Hodges]

I'm satisfied that for the task of filling a single seat in a race 
with multiple candidates, Approval voting can perform well, if the 
voters use good strategy for setting their approval threshold.

I'm wondering if anyone has done serious study of the case where 
there is a range of sophistication among voters. People vary in how 
much they follow the news, candidates may be more or less evasive, 
interest-group advertising may be more or less honest, the mass-media 
may be more or less responsible in its practice of journalism, and 
voters have different tolerance-levels for political discussion. In 
the U.S. today, a surprising fraction of the populace is working two 
jobs, a surprising fraction is not completely fluent in English, a 
surprising fraction never reads anything at all- neither books nor 
magazines nor newspapers.

Approval voting, in plain English, attempts to find the candidate 
that the greatest number of voters regard as not unacceptable. This 
is a very modest ambition. One criticism of AV is that it can favor 
mediocrity. For example in a four-candidate race, if all voters 
approve their top three, the winner may be someone ranked second or 
third by a great majority. (If they vote for "anybody but Hanson", 
they may get exactly that.) Arguably this is not a disaster- "hey, 
you marked the ballots"- AV never claims to pick the best, only the 
most-widely-acceptable. But it is still a drawback, compared to other 
voting systems that seek, by some definition, to pick the "best" 
candidate.

There are strategies for setting your approval threshold higher, that 
analytically give better results. If you know enough about the 
candidates to judge how well you like them, but nothing else, then 
approve the "best half", the candidates that are "better than the 
average candidate". If pollsters have made it clear that some are 
running well ahead of others, approve whichever of the front-runners 
you like best, plus anyone else that you like better. These 
strategies are not hard.

Still- how sensitive is AV to voters who aren't that careful? Has 
anyone done "monte-carlo" computer simulations for a few thousand 
elections, comparing cases where everyone follows some defined 
strategy with other cases where x% use that strategy and (1-x)% mark 
their ballots randomly?  If "favorite front-runner plus" gives better 
results than "best half", what fraction of the voters must be 
following FFRP to significantly improve the results, compared to 100% 
following "best half"? Questions like these.  "Sensitivity" is not 
exactly the same as "vulnerability to manipulation", but close.
-- 
------------------------------------
John B. Hodges, jbhodges@   @usit.net
The two-party system is obsolete and dysfunctional.
Better forms of democracy: www.fairvote.org
REAL CHOICES, NEW VOICES, by Douglas J. Amy