Maxim have a handy wee paper by Steve Thomas on the five electoral systems on offer in the upcoming referendum. They don’t say which one is their preference. It’s a good guide to the pros and cons of the various systems, so I’ve embedded it below.
Their summary of the five systems are:
MMP provides well for electorate representation and the representation of interests, and can provide for reasonably stable government.21 The strength of MMP is the flip-side of its drawbacks. It enables more parties to be elected to parliament, which is great for the breadth of representation, but it also gives parties a lot of power. It can also create bargaining instead of debate among parties, and a weakened accountability of the government to voters. It can also encourage interest groups to act in unhelpful ways.
FPP is simple to understand and it usually produces clear results. FPP delivers strong, stable, single party majority government most of the time, and there is usually no confusion about which party can form a government. It is easy for voters to dump a government and elect a new one since parties generally do not negotiate together to form a government.20 But, as New Zealand’s experience indicates, instances of highly disproportionate election results weakened the legitimacy of electoral outcomes and the Cabinet’s tight control over legislation and parliament weakened the public’s trust in government.21 It can also be difficult for minorities to be represented, either because safe seats make it difficult to dislodge a popular candidate or because it is difficult for minority candidates to win enough concentrated support in one electorate.
PV provides for strong electorate representation, through the election of local MPs, which usually leads to the election of single-party majority governments. That said, PV gives minor party candidates a fighting chance of winning a seat when second and subsequent preferences are used to help elect a candidate. However, it is still harder for minority candidates and parties to be represented in parliament under PV because it is not a proportional system. Further, PV can sometimes produce electoral outcomes that might not be considered entirely legitimate if the most popular candidate on first preferences does not win—although this point is debatable. While PV would enable voters to more clearly express their preferences for certain candidates it could also introduce some new ways for parties and candidates to engineer electoral outcomes, as parties would advise supportive voters how to vote to give them the best advantage.
STV is an attractive system in principle since it enables voters to indicate exactly which candidates they would like in multi-member electorates. STV enables voters to choose both between and within parties, meaning that parliament ought to reflect a wider diversity of opinions within society.22 The use of multi-member electorates also means that electoral outcomes will be more proportional.
The theoretical advantages of STV have to be weighed carefully against the practical issues with using it and the way voters tend to interact with this relatively complex system. For example, it could undermine the cohesiveness of political parties as candidates from the same party would compete against each other for election. The option of voting above-the-line can also give parties more control over which candidates are elected and in which order. In this case, many voters would not actually end up individually choosing their local MPs. In short, the advantages offered by STV could be eroded by measures to make it easier for voters to understand and use.
In trying to blend two styles of voting system, SM has some of the benefits and some of the drawbacks of both. It is neither a completely proportional system, nor does it guarantee that one party will win a large enough majority to be able to govern alone.
In terms of representation, SM has the potential to achieve a good balance between national and local representation of interests. Electorate representation would be strong, creating good ties between parliament and voters, but a quarter of parliament would also be made up of list MPs who tend to be able to represent minority interest groups well.
Because there would be more electorate MPs under SM than under MMP the major parties would benefit, but there is also a chance coalitions would be needed to form a government and that minor parties would have more representation than they typically do under single-member electorate systems, like FPP.
The document is below.