CGP Grey did a great video on STV: https://youtu.be/l8XOZJkozfI
Score Voting and Instant Runoff Voting are a bit more fair than Approval Voting, but much more difficult to implement, execute, audit, describe / educate, etc.
Both scores and approvals are ambiguous in meaning and different people with the exact same preferences would map ballot papers differently. (In situations other than standard public elections, this may not be the case: approval is great for voting on group activities where either “approve” is a binding commitment to participate if the choice is chosen, or “disapprove” is a binding opt-out if the option is chosen.)
Approval Voting seems like the best compromise between fairness and simplicity (to better ensure election integrity).
What could potentially help is to have a legislative body not determined by geography, possibly some kind of proportional party system (the downside being you need to make parties a formal part of the system, but they'll always be present anyways), that must ratify redistricting proposals and can challenge currently drawn districts.
STV with multimember districts (not the degenerate single-member district form also known as IRV) limits the degree of distortion that you can get through how district lines are drawn (whether intentional gerrymandering or otherwise.)
PR is no panacea. To avoid gerrymandering, you need an adequately high district magnitude. After all, majority-preferential is just quota-preferential with a magnitude of 1. And FPTP is just List PR with a magnitude of 1.
Anyway, I was responding to this:
>>> I don't think STV presents any function that would really prevent gerrymandering.
I still believe that STV-PR resists gerrymandering as much as List PR does.
> PR is no panacea. To avoid gerrymandering, you need an adequately high district magnitude.
I agree, but I expect any form of PR would deal a substantial blow to gerrymandering, even if it isn't a panacea. Perhaps the only way to eliminate gerrymandering is to elect all representatives from a single multi-member constituency. (I expect any other system with enough compensatory List PR seats would be practically as resistant to gerrymandering.) Of course, the sticking point for STV-PR is that a ballot paper for STV435 wouldn't be very user friendly :) .
What do you think of STV+ as a compromise? Under STV+ most representatives are elected under STV-PR and a minority are elected through compensatory List PR to increase the precision of party proportionality.
I think Germany has a good solution where there's single-winner districts along with a proportional list. I also think giving authority of redistricting to an authority that can't directly benefit from it could also work.
That is what I mean. (In theory you could have an election with one enormous constituency under STV, but I accept that it wouldn't be very practical at government level, even if it works well for electing the boards of non-profit organisations.)
> Anything involving districting is, you can still split up populations so they have weaker representation, even under proportional systems, by making their representation much weaker in many districts and overly strong in a few.
True, but if I understand correctly that's about unequal district population, rather than gerrymandering. Proportional systems with a single constituency or compensatory List PR largely avoid concerns about districting.
> I think Germany has a good solution where there's single-winner districts along with a proportional list.
Germany does indeed have a good system, but I'd prefer it without the single-winner districts and with most representatives elected by STV (ie, the STV+ system described in the last paragraph of my other post: https://news.ycombinator.com/item?id=15970289 ).
No, it's not. With any proportional system (including STV), the more members per district, the less distortion is theoretically possible through differences in how district lines are drawn.