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GP was talking about approval voting. What Queensland uses, (which they call) Preferential voting, is IRV (instant-runoff voting). That's not approval voting.

GP was talking about approval voting. What Queensland uses, (which they call) Preferential voting, is IRV (instant-runoff voting). That's not approval voting. It might initially seem like IRV's ranking (A>B>C>D>E) would be a better voting system than Approval Voting (where voters simply say A-yes, B-yes, others-no). Relative rankings seem at first glance to express more information. But it turns out that the way you have to count relative rankings either leads to pathological consequences for 3rd parties (see IRV), just like winner-takes-all voting, or the counting method becomes complex and byzantine in corner cases (see Condorcet). It's all explained on rangevoting.org

jacques_chester 8y ago
I am aware of the difference between IRV and approval voting. I am pointing out that there are examples in the wild of non-exhaustive systems being exploited. Approval is non-exhaustive by design, but even in a system where exhaustiveness had been the norm for decades a single political party in a single election was able to substantially regress its performance.
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dragonwriter 8y ago
> Preferential voting is IRV. Most real and proposed balloting methods (other than range/score voting) are preferential, they differ in the restrictions on he expressed preferences; IRV (and lots of other systems), as usually defined, relies on a fully-ranked forced-preference (no ties) ballot. Approval has an implicitly fully-ranked two-preference-rank ballot with unlimited ties, FPTP (whether plurality or majority/runoff) has an implicitly fully-ranked two-preference-rank ballot with ties allowed only in the second rank. > Relative rankings seem to express more information They do, there is no “seem". They also do so more consistently. Forced preferences can have the reverse problem of forced ties, though (which is abstractly a point in favor of unforced ranking ballots, but there's less work done on resolution procedures for them.) > but it turns out that the way you have to count relative rankings either leads to pathological consequences for 3rd parties (see IRV), just like winner-takes-all voting, or the counting method becomes complex and byzantine in corner cases (see Condorcet). Bucklin is simpler to count than IRV and doesn't have it's pathological effects; the main concrete criticism I've seen is that if truncation is allowed rather than forced-preference, and if the no-majority fallback is highest-vote-total-on-last-round, it may encourage truncation and devolve to plurality. (But a similar charge of incentive to bullet-vote is made against approval.)

jacques_chester 8y ago

I am aware of the difference between IRV and approval voting. I am pointing out that there are examples in the wild of non-exhaustive systems being exploited. Approval is non-exhaustive by design, but even in a system where exhaustiveness had been the norm for decades a single political party in a single election was able to substantially regress its performance.

deleted 8y ago
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dragonwriter 8y ago

> Preferential voting is IRV. Most real and proposed balloting methods (other than range/score voting) are preferential, they differ in the restrictions on he expressed preferences; IRV (and lots of other systems), as usually defined, relies on a fully-ranked forced-preference (no ties) ballot. Approval has an implicitly fully-ranked two-preference-rank ballot with unlimited ties, FPTP (whether plurality or majority/runoff) has an implicitly fully-ranked two-preference-rank ballot with ties allowed only in the second rank. > Relative rankings seem to express more information They do, there is no “seem". They also do so more consistently. Forced preferences can have the reverse problem of forced ties, though (which is abstractly a point in favor of unforced ranking ballots, but there's less work done on resolution procedures for them.) > but it turns out that the way you have to count relative rankings either leads to pathological consequences for 3rd parties (see IRV), just like winner-takes-all voting, or the counting method becomes complex and byzantine in corner cases (see Condorcet). Bucklin is simpler to count than IRV and doesn't have it's pathological effects; the main concrete criticism I've seen is that if truncation is allowed rather than forced-preference, and if the no-majority fallback is highest-vote-total-on-last-round, it may encourage truncation and devolve to plurality. (But a similar charge of incentive to bullet-vote is made against approval.)