In this topic I present some cases in which the Approval Voting seems to be causing problems, and I would like to know if I’m wrong.
Bad representation of interests
These are the real interests of the voters:
Group 1 (98%): A, B, C
Group 2 ( 2% ): A, B, C
These are the respective marks in AV form
Group 1 (98%): A[X], B[X], C
Group 2 ( 2% ): A, B[X], C[X]
With AV wins B even if he should win A, according to the real interests.
Here it seems clear to me that the winner should be A, but in your opinion how much should the percentage of the 2nd group increase to ensure that the victory of B is right?
In my opinion, exactly more than 40% (with group 1 less than 60%).
The groups are the same as in case 1), but with group 1 at 60% and the other at 40%.
The winner with AV is B but B isn’t the favorite of any group, therefore the following tactical votes are generated:
Group 1 (60%): A[X], B, C
Group 2 (40%): A, B, C[X]
Group 1 manages to win A thanks to its tactical votes.
In this example we note that for a voter it’s better to give the cross only to 1 candidate, the best for him (if the best is on par with others, then he will give more crosses only to those).
This type of tactical voting makes AV similar to SNTV.
There are 4 candidates A,B,C,D among which A,B are the most supported while C,D minorities.
Pluto likes D a lot and everyone else sucks (even if A is slightly better than B); Pluto could vote like this:
Honest vote: A, B, C, D[X]
In this case Pluto’s vote would be similar to a null vote being D a minority, and Pluto knows it before voting, so he decides to vote tactically:
Tactical vote: A[X], B, C, D[X]
Pluto’s vote can now influence the clash between A and B and that’s good for him, but the vote he created still supports A as much as D.
In conclusion, all voters who support minorities end up tactically supporting even 1 of the 2 most supported candidates.
This favors bipartism, even if it’s better than the single vote because at least here we see that minorities have support.
In addition to the problems seen in the case of only 1 winner, there is another.
Voters with wrong weight
By adding rules to the calculation of the results (which balance the weight of the votes) this problem is avoided.
I would like to know if these 4 cases are real AV problems or if I made some mistakes.
If you have other cases where the AV generates problems, indicate them in the reply.