Here's a model of Rural-Urban PR, followed by talk of some various forms of Rural-Urban PR.
if you have a mock election, where one party dominates in half the districts and a different party dominates in the other half, you see that a mixed STV/AV may give advantage to one or the other but also that it produces more fair overall representation than FPTP.
Here's a model of a jurisdiction where there are two districts:
if a province had just two districts: area 6 and 7 with 40 seats, under FPTP each party would take 20 seats.
if area 6 is AV, its 20 seats would go to Party B
if area 7 is STV, 12 seats to party A, 5 to party B, 2 to Party C and 1 to Party D.
so together 12 seats to party A, 25 to party B, 2 to Party C and 1 to Party D, like you say.
In this artificial example, yes, STV/AV does give advantage to Party B. it gets five more seats. But this is slight change compared to the wide changes produced by small change in votes under FPTP.
Under AV in area 6, each Party B candidate is the choice of a majority of the voters there, not always the reality under FPTP.
So STV/AV, like any system or change thereof, can benefit someone and hurt someone else, usually that is the party in power (less often it can benefit other parties instead). But a change to STV in both areas evens the field.
Under FPTP, both parties A and B are over-represented versus party C and party D which get no seats under FPTP and do get some seats where STV is even partially used.
20 districts (area #6) Party A 25 Party B 55 Party C 14 Party D 6, in each district
in 20 districts (area #7) Party A 60 Party B 24 Party C 10 Party D 6,
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If you look at a mock election, where half the districts are predominantly one party and half are predominantly another party, you see that a mixed STV/AV system may give slight advantage to one or another party, but that it gives better all-around representation than FPTP.
say half the seats are
20 districts (area #1) Party A 25 Party B 55 Party C 14 Party D 6, in each district
in 20 districts (area #7) Party A 60 Party B 24 Party C 10 Party D 6,
if a province was split evenly like that with 40 seats, under FPTP each party would take 20 seats.
if area 6 is AV 20 seats to Party B
if area 7 is STV, 12 seats to party A, 5 to party B, 2 to Party C and 1 to Party D.
so together 12 seats to party A, 25 to party B, 2 to Party C and 1 to Party D, like you say.
In this artificial example yes, STV/AV does give advantage to Party B. it gets five more seats. a slight change compared to the wide changes produced by small change in votes under FPTP.
under AV in area 6, each Party B candidate is the choice of a majority of the voters there, not always the reality under FPTP.
So STV/AV, like any system or change thereof, can benefit someone and hurt someone else, usually that is the party in power (less often it can benefit other parties instead). But a change to STV in both areas evens the field.
Under FPTP, both parties A and B are over-represented versus party C and party D which get no seats under FPTP and do get some seats where STV is even partially used.
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Rural-Urban PR
When Fair Vote Canada proposed Rural-Urban PR as one of our options for the ERRE to consider, we said
"MPs in multi-member ridings could be elected using some form of list-PR or STV. MPs in single-member ridings could be elected with preferential ballots or FPTP. The ballots used in both the single- and multi-member ridings could be similar (ranked ballots everywhere or regular ballots using a simple X everywhere)."
And "Top-up seats could be filled using either an open list system or a best runners-up system."
The best runners-up system ..."Top-up seats are filled by determining which parties win the top-up seats in each region (following the same approach as MMP) and then awarding the seats to the strongest remaining candidate from the most under-represented district for each party, just as Sweden does it." The top-up share of about 15 percent of total seats would be "achieved by increasing slightly the size of the House or the size of each riding."
This relatively-loose proposal allows different forms of Rural-Urban PR.
Rural-Urban PR is usually thought of as MMP, where Alternative Voting (Instant-runoff Voting) is used to fill rural seats, PR-STV is used to fill urban seats, and some top-up seats to improve proportionality.
That's one just possibility.
AV for rural seats is optional. It does not elect much differently than FPTP. It does have the advantage that all voters across the place would use the same voting system - preferential voting.
PR-STV is only one option for urban seats.
Straight open-list PR, like Sweden (and used at times in France), is the other.
Rural-Urban PR was inspired by a proposal by former Chief Electoral Officer Jean-Pierre Kingsley, who (like most Quebeckers) was familiar with Sweden but not with the Ireland's STV system.
Here's a link to Fair Vote Canada proposal of Rural-Urban PR:
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