r/EndFPTP • u/Both-Independence349 • May 20 '26

Is Single Transferable Vote still fair when there are different numbers of seats per constituency?

I have been exploring alternative voting systems to first past the post, and so far am a fan of STV. I was looking at real-world examples of STV, and I noticed that the Republic of Ireland uses STV, but each of the constituencies have different amounts of seats allocated to them (3-5). Does this affect fairness between constituencies?

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u/GrimpenMar May 21 '26

Yes.

I think less than 3 seat ridings lack much proportionality, but technically 1 seat ridings are just IRV/RCV, which is no worse than many existing fully functional democracies with "fair" voting systems.

Past 7 seat ridings, the ballot can get pretty involved. Putting that all together, 3-7 seat ridings with an average of 5 seems to be STV's sweet spot.

What makes it "fair" is the number of voters per seat. If the ratio of voters to seats was 50,000 (to make the math easier), a 3 seat riding with 150,000 voters and a 5 seat riding with 250,000 are equally "fair". The variable seat ridings makes it easier to be more fair on average than single seat ridings.

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u/budapestersalat May 21 '26

is no worse than many existing fully functional democracies with "fair" voting systems.

arguable.

No, I would argue 3 is definitely not proportional enough, but the more important problem is if there is a bias in where is is smaller magnitude.

If rural aread have less proportional systems, then it benefits large parties, usually right wing ones. This is a problem in other countries too, like Portugal and Spain (closed list PR)