Peter Zbornik wrote:
Hello,
an other question I wonder if you could help me with:
For single winner elections we currently use the two round system, which
is equivalent to the Contingent vote providing that the voter does not
change preferences
see http://en.wikipedia.org/wiki/Two-round_system and http://en.wikipedia.org/wiki/Contingent_vote
<http://en.wikipedia.org/wiki/Contingent_vote>According to the table on:
http://en.wikipedia.org/wiki/Schulze_method#Comparison_with_other_preferential_single-winner_election_methods,
Contingent voting
<http://en.wikipedia.org/wiki/Sri_Lankan_contingent_vote> has no
advantage over Schulze method (apart from being a few dimensions simpler
in terms of vote count and understandability for the common person).
Two-round voting (although widely used) is not listed in the table.
The questions are:
1) Does the two-round system satisfy any criteria, which Schulze method
fails, apart from complexity and understandability and the option to
change preferences between election rounds?
If voters vote exactly the same way in both rounds, and there are three
candidates, the two-round method is equal to IRV. In this case, it
passes LNHarm while Condorcet does not.
If the voters don't, then it makes no sense to apply criteria to the
two-round system as a whole. If you did, you could make the two-round
system fail Majority unless it had a rule stating that there would be no
second round in case of a majority preference. Just have a majority vote
for A, the minority for B, then in the second round, have everybody vote
for B.
2) What criteria does the two-round system satisfy that the Contingent
vote does not satisfy and vice versa?
See above. One can't apply criteria that applies to a single ballot set
to a two-round method if the voters change their preferences between the
rounds. If they don't, then the two-round method is simply the
Contingent vote and so the compliances must be equal.
----
Election-Methods mailing list - see http://electorama.com/em for list info
