In New Zealand they’re gearing up for a general election and a referendum on whether to change the voting procedure.
New Zealand currently uses MMP, or the Mixed Member Proportional system of representation. Every voter has two votes. They vote for the person they want to represent their electoral region, and they vote for which party they want to form the government. The overall make up of the parliament has to respect the proportions of support parties achieve in this second party vote. So if party A garners 15% support in the party vote, it has to have around 15% of the MPs in the eventual parliament.
Some of the MPs in the parliament are directly elected by voting public by winning the contests in their electoral regions. I think in the 2011 election there will be 63 electorate MPs, 7 Maori MPs and 50 list-MPs elected indirectly via the party vote system. The MPs who represent regions win their seat by gaining the largest number of votes, but this is never or nearly never a majority of the electorate. The Maori MPs are elected on the same basis; they represent regions, but their constituents chose to be on a separate, parallel Maori-only electoral roll instead of on the general register. Pakeha can stand for election as Maori MPs but can’t vote for them.
Once the 70 electorate/Maori-MPs have been determined and their party affiliations noted, the overall makeup of parliament is determined by the party vote and parties that are under-represented in terms of the number of electorate seats they won are topped up with MPs drawn from a list. (Parties have to announce their lists before the election so the voting public knows who will take any seats the parties win.)
There are a couple of further complications, such as a threshold that a party needs to reach to get list-MPs (to prevent a very fractured parliament), but that’s basically it. It’s a wee bit involved but not excessively complicated. Summary: two votes; one for a person, one for a party. Makeup of parliament fixed by party vote.
The referendum will put a two part question to the voting public: a) Should New Zealand keep the Mixed Member Proportional (MMP) voting system? and b) if New Zealand were to switch to another voting system, which voting system would you choose?
There are four options, and you get to pick one, not put them in the order of your preference.
First Past the Post (FPP): The old system. You vote for a person to represent your region. The person with the most votes wins the seat.
Preferential Voting (PV): Put the candidates representing your region in order of your preference. If no one gets more than fifty percent of the first preference votes cast, the candidate with the fewest first preference votes is eliminated and their votes are redistributed among the remaining candidates until someone crosses the fifty percent mark. I think this is the same as the Alternative Vote (AV) system that was rejected in the UK earlier this year.
Single Transferable Vote (STV): The Irish System. There are multi-seat constituencies. In New Zealand it would most likely be 4-7 MPs per constituency. You put the candidates in the order of your preference. Those meeting the quota are elected, others are eliminated and their votes are redistributed according to their voters’ next preferences until all the seats are filled.
Supplementary Member (SM): This one is like MMP except that the party vote doesn’t determine the make up of parliament as a whole, but rather the proportion of the list-MPs a party has matches the proportion of the party vote it wins. That is, you vote for a person and a party. If party A gets 15% of the party vote, then it gets 15% of the list-MPs (currently 50 in New Zealand) rather than 15% of the overall parliament (currently 120 MPs).
I’m not entitled to vote in this election (having been absent from New Zealand for so long), but if I were, I’d vote to keep MMP, but if we were to change, I’d opt for preferential voting (PV). I really like the fact that preferential voting ensures that whoever wins the seat always has the backing of a majority of the electorate in that region (even if they are not always everybody’s first choice).
I do think proportionality is a virtue of electoral systems, but none of the alternatives on the referendum are as proportional as MMP. If proportionality is what is important in a voting system, stick with MMP. The supplementary member system is obviously less proportional, because the bearing of the party vote on the overall makeup of parliament is reduced. FPP is not proportional and neither is PV.
STV is somewhat proportional. The proportionality comes into the picture not through the preferential voting regime, but by having multi-seat constituencies. It means you don’t have a winner takes all affair where one party claims all the parliamentary representation of that constituency. Instead it’s broken into chunks and the parties votes are ’rounded’ to the nearest chunk. In a four seat constituency, a chunk is just over 20% of the votes cast, so a party with 38% percent of the popular vote may get two seats, while one with 23% and another with 17% both get just one. The remaining parties with 22% between them get nothing. This is proportionality for the big and middle sized parties only.
For me it’s a toss up between PV and STV. I think PV edges it. One of the criticisms you hear about STV here in Ireland is that it means that MPs from the same party, who are hoping all to win seats in the same constituency, are actually competing against each other more intensely than candidates from different parties, because they’re after the first preference votes of the same party members (they usually can’t both get elected), whereas candidates from different parties are competing for the preferences of different groups of people and usually can both get elected. This means MPs have a strong incentive to prioritise pleasing their immediate local constituents at the expense of thinking about the broader good of the country. Seán MP will always vote for fixing potholes in Bally-end-of-beyond, because if they don’t they’ll lose their seat to another challenger from within the same party. There can’t be this sort of intra-party rivalry in single seat preferential voting.
Of course this is not the only relevant consideration by any means.