Comment Re:Why choose approval voting though? (Score 1) 416
EVERY deterministic voting method is susceptible to tactical voting. That is mathematically proven. With Approval Voting however, voters NEVER have to fear supporting their sincere favorite candidate. It passes the Favorite Betrayal Criterion unlike virtually every ranked system. If you think it's bad for voters to have to ponder whether or not to support a SECOND favorite candidate, imagine how bad it is to have a system in which you are generally encouraged not to support your FAVORITE unless that candidate has a strong chance of winning. See ScoreVoting.net/FBCsurvey.html
The analysis doesn't take into account the effect that the probability of regret will have on the level of tactical voting.
The general point here is, what about the case where there's more tactical voting with Approval Voting than with some other system. First of all, there's no evidence for that. For most ranked voting methods, voters generally use the Naive Exaggeration Strategy, meaning that tactical voting is used by something like 80-90% of voters. And that's actually, coincidentally, the generally correct strategy for ranked systems.
Here's a page in which we compared the performance of voting methods based on whether 100% or 50% of voters are sincere. Note that Approval Voting performs better with fully half of the voters being tactical than most other methods do with NO tactical voting whatsoever. This accounts for the differential tactical-ness you propose.
Lastly, there are two theorems that specifically describe how tactical voting with Approval Voting actually leads to mild (some would say, good) results.
Tends to elect Condorcet winners when they exist: ScoreVoting.net/AppCW.html
Maximizes the number of pleasantly surprised voters: ScoreVoting.net/PleasantSurprise.html