“Effective Seat Product” for two-tier PR (including MMP) and MMM

The seat product for a simple electoral system is its assembly size (S) times its mean district magnitude (M) (Taagepera 2007). From this product, MS, the various formulas of the Seat Product Model (SPM) allow us to estimate the effective number of parties, size of the largest, disproportionality, and other election indicators. For each output tested in Shugart and Taagepera (2017), Votes from Seats, we find that the SPM explains about 60% of the variance. This means that these two institutional inputs (M and S) alone account for three fifths of the cross-national differences in party system indicators, while leaving plenty for country-specific or election-specific factors to explain as well (i.e., the other 40% of the variance).

The SPM, based on the simple seat product, is fine if you have a single-tier electoral system. (In the book, we show it works reasonably well, at least on seat outputs, in “complex” but still single-tier systems like AV in Australia, majority-plurality in France, and STV in Ireland.) But what about systems with complex districting, such as two-tier PR? For these systems, Shugart and Taagepera (2017) propose an “extended seat product”. This takes into account the basic-tier size and average district magnitude as well as the percentage of the entire assembly that is allocated in an upper tier, assumed to be compensatory. For estimating the expected effective number of seat-winning parties (NS), the extended SPM formula (Shugart and Taagepera, 2017: 263) is:

NS=2.5t(MB)1/6,

where MB is the basic-tier seat product, defined as the number of seats allocated in the basic tier (i.e., assembly size, minus seats in the upper tier), and t is the tier ratio, i.e., the share of all assembly seats allocated in the upper tier. If the electoral system is simple (single tier), the equation reduces to the “regular” seat product model, in which MS=MB and t=0.

(Added note: in the book we use MSB to refer to what I am calling here MB. No good reason for the change, other than blogger laziness.)

We show in the book that the extended seat product is reasonably accurate for two-tier PR, including mixed-member proportional (MMP). We also show that the logic on which it is based checks out, in that the basic tier NS (i.e., before taking account of the upper tier) is well explained by (MB)1/6, while the multiplier term, 2.5t, captures on average how much the compensation mechanism increases NS. Perhaps most importantly of all, the extended seat product’s prediction is closer to actually observed nationwide NS, on average, than would be an estimate of NS derived from the simple seat product. In other words, for a two-tier system, do not just take the basic-tier mean M and multiply by S and expect it to work!

While the extended seat product works quite well for two-tier PR (including MMP), it is not convenient if one wants to scale such systems along with simple systems. For instance, as I did in my recent planting on polling errors. For this we need an “effective seat product” that exists on the same scale as the simple seat product, but is consistent with the effect of the two-tier system on the effective number of parties (or other outputs).

We did not attempt to develop such an effective seat product in Shugart and Taagepera (2017), but it is pretty straightforward how to do it. And if we can do this, we can also derive an “effective magnitude” of such systems. In this way, we can have a ready indicator of what simple (hypothetical) design comes closest to expressing the impact of the (actual) complex design on the party system.

The derivation of effective seat product is pretty simple, actually. Just take, for the system parameters, the predicted effective number of seat-winning parties, NS, and raise it to the power, 6. That is, if NS=(MS)1/6, it must be that MS=NS6. (Taagepera 2007 proposes something similar, but based on actual output, rather than expected, as there was not to be a form of the seat product model for two-tier systems for almost another decade, till an initial proposal by Li and Shugart (2016).)

Once we do this, we can arrive at effective seat products for all these systems. Examples of resulting values are approximately 5,000 for Germany (MMP) in 2009 and 6,600 for Denmark (two-tier PR) in 2007. How do these compare to simple systems? There are actual few simple systems with these seat products in this range. This might be a feature of two-tier PR (of which MMP could be considered a subtype), as it allows a system to have a low or moderate basic-tier district magnitude combined with a high degree of overall proportionality (and small-party permissiveness). The only simple, single-tier, systems with similar seat products are Poland (5,161), with the next highest being Brazil (9,747) and Netherlands before 1956 (10,000). The implication here is that Germany and Denmark have systems roughly equivalent in their impact on the party system–i.e., on the 60% of variance mentioned above, not the country-specific 40%–as the simple districted PR system of Poland (S=460, M=11) but not as permissive as Brazil (S=513, M=19) or pre-1956 Netherlands (M=S=100). Note that each of these systems has a much higher magnitude than the basic-tier M of Germany (1) or larger assembly than Denmark (S=179; M=13.5). Yet their impact on the nationwide party system should be fairly similar.

Now, suppose you are more interested in “effective district magnitude” than in the seat product. I mean, you should be interested in the seat product, because it tells you more about a system’s impact on the party system than does magnitude alone! But there may be value in knowing the input parameters separately. You can find S easily enough, even for a complex system. But what about (effective) M? This is easy, too! Just take the effective seat product and divide it by the assembly size.

Thus we have an effective M for Germany in 2009 of 7.9 and for Denmark in 2007 of 36.9. These values give us an idea of how, for their given assembly sizes, their compensatory PR systems make district magnitude “effectively”–i.e., in terms of impact on the inter-party dimension–much larger than the basic-tier districts actually are. If we think low M is desirable for generating local representation–a key aspect of the intra-party dimension–we might conclude that Germany gets the advantages M=1 in local representation while also getting the advantages of the proportionality of 8-seat districts. (Best of both worlds?) By comparison, simple districted PR systems with average M around 8 seats include Switzerland and Costa Rica. (The Swiss system is complex in various ways, but not in its districting.) Eight is also the minimum magnitude in Brazil. Denmark gets whatever local representation advantages might come from an actual mean M of 13.5, yet the proportionality, for its assembly size, as if those districts elected, on average, 37 members. Actual districts of about this magnitude occur only in a relatively few districts within simple systems. For instance, the district for Madrid in Spain has M in the mid-30s, but that system’s overall average is only 6.7 (i.e., somewhat smaller than Germany’s effective M).

Now, what about mixed-member majoritarian (MMM) systems. Unlike MMP, these are not designed with a compensatory upper tier. In Votes from Seats, Taagepera and I basically conclude that we are unable to generalize about them. Each system is sui generis. Maybe we gave up too soon! I will describe a procedure for estimating an effective seat product and effective magnitude for MMM systems, in which the basic tier normally has M=1, and there is a list-PR component that is allocated in “parallel” rather than to compensate for deviations from proportionality arising out of the basic tier.

The most straightforward means of estimating the effective seat product is to treat the system as a halfway house between MMP and FPTP. That is, they have some commonality with MMP, in having both M=1 and a list-PR component (not actually a “tier” as Gallagher and Mitchell (2005) explain). But they also have commonality with FPTP, where all seats are M=1 plurality, in that they reward a party that is able to win many of the basic seats in a way that MMP does not. If we take the geometric average of the effective seat product derived as if it were MMP and the effective seat product as if it were FPTP, we might have a reasonable estimate for MMM.

In doing this, I played with both an “effective FPTP seat product” from the basic tier alone and an effective FPTP seat product based on assuming the actual assembly size. The latter works better (in the sense of “predicting,” on average for a set of MMM systems, what their actual NS is), and I think it makes more logical sense. After all, the system should be more permissive than if were a FPTP system in which all those list-PR component seats did not exist. So we are taking the geometric average of (1) a hypothetical system in which the entire assembly is divided into a number of single-seat electoral districts (Eeff) that is Eeff = EB+tS, where EB is the actual number of single-seat districts in the basic tier and S and t are as defined before, and (2) a hypothetical system that is MMP instead of MMM but otherwise identical.

When we do this, we get the following based on a couple sample MMM systems. In Japan, the effective seat product becomes approximately 1,070, roughly equivalent to moderate-M simple districted PR systems in the Dominican Republic or pre-1965 Norway. For South Korea, we would have an effective seat product of 458, or very roughly the same as the US House, and also close to the districted PR system of Costa Rica.

Here is how those are derived, using the example of Japan. We have S=480, with 300 single-seat districts and 180 list-PR seats. Thus t=0.375. If it were two-tier PR (specifically, MMP), the extended seat product would expect NS=3.65, from which we would derive an effective seat product, (MS)eff=3.666 =2,400. But it is MMM. So let’s calculate an effective FPTP seat product. Eeff = EB+tS=300+180=480 (from which we would expect NS=2.80). We just take the geometric mean of these two seat-product estimates: (2400*480)1/2=1,070. This leads to an expected NS=3.19, letting us see just how much the non-compensatory feature reduces expected party-system fragmentation relative to MMP as well as how much more permissive it is than if it were FPTP.

How does this work out in practice? Well, for Japan it is accurate for the 2000 election (NS=3.17), but several other elections have had much NS lower. That is perhaps due to election-specific factors (producing huge swings in 2005 and 2009, for example). As I alluded to above already, over the wider set of MMM systems, this method is pretty good on average. For 40 elections in 17 countries, a ratio of actual NS to that predicted from this method is 1.0075 (median 0.925). The worst-predicted is Italy (1994-2001), but that is mainly because the blocs that formed to cope with MMM contained many parties (plus Italy’s system had a partial-compensation feature). If I drop Italy, I get a mean of 1.0024 (but a median of only 0.894) on 37 elections.

If we want an effective magnitude for MMM, we can again use the simple formula, Meff=(MS)eff/S. For Japan, this would give us Meff=2.25; for Korea Meff=1.5. Intuitively, these make sense. In terms of districting, these systems are more similar to FPTP than they are to MMP, or even to districted PR. That is, they put a strong premium on the plurality party, while also giving the runner-up party a considerable incentive to attend to district interests in the hopes of swinging the actual district seat their way next time (because the system puts a high premium on M=1 wins, unlike MMP). This is, by the way, a theme of the forthcoming Party Personnel book of which I am a coauthor.

(A quirk here is that Thailand’s system of 2001 and 2005 gets an effective magnitude of 0.92! This is strange, given that magnitude–the real kind–obviously has a lower limit of 1.0, but it is perhaps tolerable inasmuch as it signals that Thailand’s MMM was really strongly majoritarian, given only 100 list seats out of 500, which means most list seats would also be won by any party that performed very well in the M=1 seats, which is indeed very much what happened in 2005.)

In this planting, I have shown that it is possible to develop an “effective seat product” for two-tier PR systems that allows such systems to be scaled along with simple, single-tier systems. The exercise allows us to say what sort of simple system an actual two-tier system most resembles in its institutional impact on inter-party variables, like the effective number of seat-winning parties, size of the largest party, and disproportionality (using formulas of the Seat Product Model). From the effective seat product, we can also determine an “effective magnitude” by simply dividing the calculated effective seat product by actual assembly size. This derivation lets us understand how the upper tier makes the individual district effectively more proportional while retaining an actual (basic-tier) magnitude that facilitates a more localized representation. Further, I have shown that MMM systems can be treated as intermediary between a hypothetical MMP (with the same basic-tier and upper-tier structure) and a hypothetical FPTP in which the entire assembly consists of single-seat districts. Again, this procedure can be extended to derive an effective magnitude. For actual MMP systems in Germany and also New Zealand, we end up with an effective magnitude in the 6–8 range. For actual MMM systems, we typically get an effective magnitude in the 1.5–3 range.

I will post files that have these summary statistics for a wide range of systems in case they may be of use to researchers or other interested readers. These are separate files for MMM, MMP, and two-tier PR (i.e, those that also use PR in their basic tiers), along with a codebook. (Links go to Dropbox (account not required); the first three files are .CSV and the codebook is .RTF.)

Added note: In the spreadsheets, the values of basic-tier seat product (MB) and tier ratio (t) are not election-specific, but are system averages. We used a definition of “system” that is based on how Lijphart (1994) defines criteria for a “change” in system. This is important only because it means the values may not exactly match what you would calculate from the raw values at a given election, if there have been small tweaks to magnitude or other variables during an otherwise steady-state “system”. These should make for only very minor differences and only for some countries.

NZ 2020: Strategic coalition voting?

Earlier, I noted that in the New Zealand 2020 election, the Labour Party flipped several seats in mostly rural single-seat districts that are normally strongholds of the National Party.

Commenting on those swings, North Canterbury Federated Farmers president Cameron Henderson said:

There were definitely “strategic farmers” voting Labour in an effort to avoid a Labour-Greens government.

He added a caveat, that most of the vote swings in these seats came from urban voters within predominantly rural electorates. Nonetheless, his confidence that there were strategic farmers is a nice anecdote regarding what some political scientists have regarded as strategic voting motivated not by who can win locally but by which parties may form government.

As I noted in my election preview in late July, there were only two likely outcomes of this election: A Labour–Green coalition or a Labour single-party majority. There were no occasions over the last several months when a National-led government was likely based on any publicly available evidence. For most farmers, a government in which the center-left Labour Party has a parliamentary majority is a much more palatable outcome than one in which that party needs the Greens for its majority.

MMP in NZ: An example of “best of both worlds” in action

In Shugart and Wattenberg (2001) we ask if mixed-member systems offer a “best of both worlds.” That is, do they allow simultaneously for the benefits of local representation and individual-member accountability that are the (supposed) advantages of single-seat plurality (FPTP) and the representation of smaller national parties that might struggle to win districts but would be represented under proportional representation (PR).

There was a question mark in the book’s subtitle. Over time, I have come to believe that indeed the proportional type (MMP) does have a strong tendency to offer the best of both worlds. The reason is that members elected in districts have incentives to behave as local representatives at the time that there is close approximation between party vote and seat shares (assuming compensation is carried out nationwide or in large regions). The majoritarian type (MMM, as in Japan and Taiwan) probably does not; it is much closer in its overall incentive structure to FPTP, even though it does indeed permit smaller national parties to win seats.

For MMP, the “best of both worlds” argument assumes that parties nominate dually–meaning many elected members will have run in a district and had a (realistically electable) list position simultaneously. If they do, then even the list-elected members will have a local base, and should have incentives to act as the local “face” of the party, including possibly by offering constituent services. Both prior anecdotes I have shared from New Zealand (e.g., “shadow MPs” who win from the list and maintain a local office) and my forthcoming coauthored book, Party Personnel, offer further evidence that MMP does indeed work in this way.

Now comes a terrific anecdote from New Zealand’s 2020 election. In this election, Labour won a majority of seats (64/120) with 49.1% of the nationwide party list vote. In the nominal tier of single-seat districts (electorates) it won 43 of the 72 available seats. Its win included some districts that are normally strongholds of the center-right National Party (which won 35 seats overall and just 26 districts).

Commenting on some of the Labour wins in mostly rural districts, Federated Farmers president Andrew Hoggard said:

in some “flipped” electorates Labour list MPs had worked hard to raise their profile and get involved with the community and this had paid off when they campaigned for the electorate.

This is an ideal description of how the “best of both worlds” argument works: list-elected members have incentives to attend to local needs of the district in which they ran for the nominal seat (but “lost”) in hopes of capturing the local plurality in the next election.

Of course, there were other factors at work as well. I will offer another planting about one of those factors separately. There is also some uncertainty at this stage just exactly the degree to which rural voters flipped, as the wins may have come in significant part from very large swings in the town areas within districts that also include large rural areas. Regardless, MMP offers the key advantage of giving most elected members, if dually nominated, a tie to a local constituency while ensuring close approximation of overall seat totals to party-list votes.

Tweaks to MMP in Germany?

I am aware that there have been ongoing efforts to introduce some small reforms in the mixed-member proportional (MMP) system in Germany. The main challenge is to prevent the Bundestag from expanding so much in size, since a Constitutional Court ruling mandated full compensation.

The brief background is that the system has long had the potential for adding seats to cope with “overhangs”, which happen when a party in a state wins more districts than its party-list share would entitle it to. The Court ruled that the procedure in place over many elections still left the system unacceptably disproportional. (Manuel posted a good primer on the changes back in 2013; see also a long and interesting comment thread here on F&V.)

There are proposals currently being considered in the Bundestag that would attempt to limit the expansion in the chamber’s size that the current system allows. For instance, in 2017, the size went from the basic 598 (299 nominal and initially as many list) to 709 (401 list seats!).

The article I have is from AP, and (predictably) is thin on detail. All it says in the way of substance is:

The new proposal mainly involves keeping the number of constituencies unchanged in the 2021 election but slightly reducing the number of extra seats. By the time of the 2025 election, it calls for the number of constituencies to be cut to 280. A reform commission is supposed to produce a detailed plan.

The article also notes that opposition parties “weren’t impressed.”

I hope some readers might have more detail on what is being proposed.

NZ2020: Maori Party list-candidate attributes and “burning bridges”

The New Zealand Maori Party has introduced its party list for the 2020 election, now set for 17 October. The press release boasts of the backgrounds of the candidates, including some sports celebrities and experienced local officeholders. Interestingly, one of the co-leaders has adopted a “burning bridges” strategy–being placed too low on the list (7th) to be elected if he does not win his district (electorate) under New Zealand’s mixed-member proportional (MMP) system. (In some past elections, the party has won only district seats; it did not win any seats at all in 2017.)

The press release says, in part:

In our list we have champion athletes: the founder of Iron Māori (Heather Te Au Skipworth); a coordinator for the diploma in sport and recreation- and a crossfit trainer (Fallyn Flavell); a fourth dan black belt in aikido (Mariameno Kapa-Kingi) and competitive rower (Tumanako Silveria).

We have candidates with vast expertise and experience in local government (Merepeka Raukawa-Tait, Elijah Pue, John Tamihere, Rangi Mclean, Debbie Ngarewa-Packer); a former Cabinet Minister Hon Tamihere; two past youth MPs (Eru Kapa-Kingi and Elijah Pue); and former candidates for the Māori Party, Mana Motuhake, Alliance Labour, and the Christian Heritage Party.

It also has this lovely nugget:

“We are campaigning on the mantra of MMP: More Māori in Parliament” said Che Wilson [party president].

Regarding co-leader John Tamihere, Waatea News quotes him as explaining his taking such a low list position:

This is the Māori thing to do and I could not go back to Parliament if I didn’t have the mandate of the people on the street… My six fellow candidates have put themselves and their whānau up for this challenge and this is my way of showing my support for their sacrifice.

In 2017, the party was within five percentages points in only one of the Maori set-aside electorates, Te Tai Hauāuru. Labour won all seven of them. Back to 2014, the party won two of the electorates, plus one list seat (which I believe is the only list seat it has ever won).

I have not seen polling of the Maori electorates. Perhaps someone reading this has. But with Labour currently running so far ahead of its 2017 showing in national polls, it would seem the Maori candidates have their work cut out for them if the party is to recover.

(The idea of candidates in mixed-member systems “burning bridges” by not taking an electable list rank comes from Krauss, Nemoto, and Pakennen, 2011.)

South Korea 2020

South Korea had its assembly election on 15 April, with various covid-19 precautions in place. The Democratic Party of President Moon Jae-in (elected in 2017) won a majority of seats.

As discussed previously at F&V, the electoral system was changed from mixed-member majoritarian (MMM) to, at least partially, mixed-member proportional (MMP) prior to this election. It is only partially MMP not mainly because the number of compensatory list seats is so small (30 out of 300 total), but because there remain 17 seats that are, apparently, allocated in parallel (i.e., as if it were MMM).

There was some discussion in various media accounts (and in the previous thread) of the major parties setting up “satellite” parties to “game” the MMP aspect of the system. Under such a situation, a big party will contest the nominal tier seats and use a separate list to attract list votes and seats. By not linking its victorious nominal candidates with a same-party list, a party can gain extra seats, vitiating the compensation mechanism that defines MMP. This is what happened in Lesotho in 2007, for example. (That thread has an interesting series of comments about the issue, including why German parties do not do this in their MMP system.)

The Democratic Party set up a Together Citizens Party to compete for list seats and the main opposition United Future Party set up a Future Korea Party to do the same.

However, if I understand the results correctly (at Wiki), it seems the satellite was not necessary for the Democratic Party to win its seat majority. The Democrats won 163 constituency seats on 49.9% of the (nominal) vote; with 300 total seats, this is a majority no matter what happens with the list seats. Their satellite won 17 seats on 33.4% of the list votes. The United Future won 84 nominal seats on 41.5% of the nominal vote; their satellite won 19 seats on 33.8% of the list votes. I am finding these numbers hard to understand! Maybe someone else can figure this out for us.

Lithuania threshold reduction

The Lithuanian parliament has passed an amendment to the country’s electoral law. If it secures final passage, as expected, the threshold for party-list seats will be reduced from 5% to 4% for parties running alone and from 7% to 5% for electoral coalitions.

A proposal to reduce the assembly size from 141 to 121 was defeated in a referendum in May.

(Source: Linas Eriksonas, 2019)

Note that Lithuania has a mixed-member majoritarian (MMM) system: 70 of 141 legislators are elected in single-seat districts, the rest by list PR (nationwide, non-compensatory). The legal threshold affects only the list component.

South Korea moving to MMP?

South Korea’s National Assembly appears close to passing an electoral reform bill. It seems that it would change the existing mixed-member majoritarian (MMM) system to mixed-member proportional (MMP).

I always take media reports about important details of electoral systems with caution, but it seems the list seats will be made compensatory: “Under MMP, parliamentary seats are tied to the percentage of voters’ support for political parties.”

The current system (as of 2016) has 47 non-compensatory list seats, in a 300-member assembly.

However, there is a catch. The article says, “The number of PR posts to be allocated under the MMP representation scheme will be capped at 30.” Yet there are to remain 47 list seats; how are the other 17 allocated? To the largest party, or based on vote shares without taking district wins into account (as under MMM)? I wish it were clear, as such details would make quite a difference.

Regardless, proportionality will be quite limited.

An earlier provision of the reform bill that would have provided for 75 list seats was turned down.

Maybe we can call the new system MMp. Maybe.

Thanks to FairVote Vancouver and Kharis Templeman for the tip.

Quebec to have electoral reform referendum

Per CTV News Montreal, the CAQ governing party in Quebec promises a referendum on a specific electoral-reform proposal to be held concurrent with the next general election in 2022.

The CAQ government on Wednesday introduced its electoral reform law, but backed away from its 2018 campaign promise to have it in place in time for the next general election.

The system is a form of mixed-member proportional representation (MMP), but a complex one. And not very proportional.

The number of seats in the National Assembly would remain 125. The new electoral law would divide Quebec into 80 larger electoral divisions that will mainly be the same as federal ridings, and 17 wider regions:

  • 80 MNAs would be elected according to the current system

  • 45 MNAs on a list of candidates would be divided among the parties, according to the percentage of votes obtained in the 17 regions

Thirty six percent of seats for the list tier is certainly on the small side, and the proportionality would be reduced further by that list tier itself being districted. Note that the mean number of seats per compensation region is only 2.65.

Based on further detail that I learned from Manuel on Twitter (and that I trust he will not mind my sharing here), we can see yet more ways that this proposal is designed to limit proportionality.

…it’s a very constrained implementation of PR, limited by a provincial-level 10% (yes, ten percent) threshold; and districted MMP in seventeen regions, with a new variation of the D’Hondt rule that skews seat distributions in favor of the larger parties.

Regarding the seat allocation method for the compensation seats (which will limit how compensatory it actually will be):

In Scotland and Wales the modified D’Hondt divisors are N+1,N+2,N+3, and so on, where N = number of single-member seats. In the Quebec proposal, they are N/2 + 1, N/2 + 2, N/2 + 3, N/2 being *half* the number of single-member seats, rounded up, and resulting in lower divisors.

One additional detail: the bill provides for separate allocations of single-member and PR list seats among regions – according to the number of registered voters – which guarantee all but one region a minimum of two seats. This would cost Montreal – a PLQ bastion – three seats.

I would still consider this MMP*, as there is a compensation mechanism. I am on record as considering even the Jenkins Commission proposal in the UK to be MMP, albeit with lots of caveats given it was also designed to be about as weak on the P as could be.

Regarding the election of 2018 when the CAQ came into power–surprisingly, with an absolute majority of seats–and the electoral-reform promises made at the time, see this earlier planting.


  • * UPDATE: I am now not sure about this; I need more time to think it through, and that will have to wait till some time in 5780! In the meantime, see this Twitter thread. I think the issue hinges on whether the “modification” to D’Hondt is actually more like Imperiali. While Taagepera and I list Imperiali divisors in our book as being part of the family of PR allocation formulas, we both now believe that it should not be. We were prompted to this view by an email exchange earlier in 2019 with Steven Verbanck (regular F&V commenter). Anyway, to be continued…

PEI 2019: Provincial assembly election and MMP referendum

Prince Edward Island election day was today. Results appear to be pointing towards a lead in votes and seats for the Progressive Conservatives. Thus the expectation (at least according to some polling) that the Greens might form the government looks unlikely now. The Green Party appears to be in second place, although closer (in votes) to the third place Liberals than to first place. The Liberals are the outgoing governing party, with a seat majority.

It looks like it will be a minority situation, which I think will be a first for PEI.

Voters were also voting in a referendum on whether to replace FPTP with a mixed-member proportional (MMP) system, with the voter brochure showing it as an open-list variant. That looks like a close call at this point, but most likely it has been defeated. To pass, the MMP proposal requires not only a majority of votes, but also a win in 17 of the 27 districts. At the moment, CBC is reporting it will win no more than 15 (and may not have a provincewide majority anyway).

PEI has been here before, having voted in a non-binding ballot (conducted by phone or online) for MMP in 2016, and having defeated an earlier MMP referendum by a big majority in 2005.

Today’s referendum had an odd ballot format: the NO option appears above the YES option. I am not sure I have ever seen that before.

(There is one district that did not vote today in the assembly election; a candidate, of the Greens, died in a canoe accident last Friday, so there will be a by-election at a future date.)

New Zealand to have referendum questions on 2020 ballot, potentially including “tweaks” to MMP

Earlier in December, the Justice Minister of New Zealand, Andrew Little (Labour) announced that there would be a binding referendum on recreational cannabis use concurrent with the 2020 general election. There may also be a question on euthanasia, and–of core interest to this blog–electoral reform.

Earlier, Little had said:

It has been floating around that if we’re going to do a bunch of referenda, why wouldn’t we put this question about whether we want to make those final tweaks to MMP, reduce that 5 per cent threshold to 4 per cent, get rid of the one-seat coat-tailing provision.

These proposals were part of the Electoral Commission’s MMP Review, but the government at the time (National-led) did not act on them.

The multiparty nature of the New Zealand political system that MMP has institutionalized is apparent in these issues being on the table. Having a referendum on cannabis use was a provision of the confidence and supply agreement that Labour signed with the Green Party after the 2017 election. In addition, Labour’s other current governing partner, New Zealand First, has indicated support for a bill on euthanasia sponsored by the leader of ACT, another of the smaller parties (a right-wing partner to opposition National).

Both provisions that the MMP Review recommended changing have had past impacts on current parties. The ACT has depended for its representation in parliament on the so-called coat-tailing provision (a term I do not like for the alternative threshold) in several elections. The New Zealand First once was left out of parliament for having a vote share between 3.5% and 5%, despite other parties (including ACT) being represented, due to winning a single district (electorate) plurality. (Obviously, 4% would not have helped NZF in 2008, as it had only 3.65%. But the point is that the current provisions produce potential anomalies; I have suggested before that the two thresholds should be brought closer to one another.)

Also of note: Little said that the cabinet had discussed, but decided against, having a citizen’s assembly to deliberate issues related to cannabis (and perhaps also euthanasia).

The gaming of Mexico’s PR disparity cap

One distinctive feature of Mexico’s 500-seat Chamber of Deputies’ mixed-member majoritarian system – under which 300 members are chosen by plurality voting in as many congressional districts, while the remaining 200 seats are filled by party-list proportional representation (initially determined on a nationwide basis) – is a provision which caps party representation at a maximum of eight percentage points above its national proportion of votes cast for parties entitled to participate in the distribution of PR mandates (in addition, no party may have a total number of Chamber seats in excess of 300 mandates). However, in recent years some parties running in electoral coalitions have successfully gamed the system to circumvent the limits imposed by this provision, effectively diluting its intended compensatory effects.

The eight percent disparity cap is implemented by determining the maximum number of Chamber seats each party may obtain; if a party exceeds this amount, its PR seat allocation is reduced so that its total number of plurality and list seats is equal to the capped seat total. For example, in the 1997 legislative election – generally regarded as Mexico’s first truly free and fair vote – the then-ruling Institutional Revolutionary Party (PRI) won 38% of the total vote and 39.98% of the “effective national vote” (“votación nacional efectiva” in Spanish), that is the total number of votes cast for parties entitled to take part in the allocation of PR seats. Therefore, PRI could obtain at most 47.98% (39.98% plus 8%) of the Chamber’s 500 seats, or 239 seats, disregarding fractions. Since PRI had won 165 of 300 plurality mandates in the election, and had been initially assigned 80 PR seats, for a total of 245 seats – six above the capped total – the party’s list mandates were reduced to 74 seats (239 minus 165); the remaining 126 PR mandates were then distributed among the other four qualifying parties.

Prior to 2008, Mexican voters could choose either a party running alone or a coalition, but not a specific party running within a coalition. Therefore, coalitions were treated as parties when it came to allocating Chamber seats and determining the eight percent cap. However, a 2008 electoral reform allowed voters to choose parties running as part of a coalition, and at the same time limited coalitions to plurality elections only. Since then, the distribution of Chamber PR seats has been carried out entirely on an individual party basis, even though coalitions have often continued to determine the outcome of plurality races; most importantly, the allocation of plurality seats among coalition partners has been determined on the basis of officially registered coalition agreements (“convenios de coalición” in Spanish). In due course, larger parties running in coalition with smaller allies discovered they could game the cited provision by assigning plurality seats in the coalition agreement to their junior partners, while these in turn nominated candidates who were actually members of the larger party. In this manner, the larger party artificially reduced its total number of seats, thus making it less likely that it would hit the eight percent cap during the allocation of PR list mandates.

Before 2018, PRI and its ally the Ecologist Green Party of Mexico (PVEM) gamed the system in the manner described, but the scope of their scheme was comparatively limited, not least because PVEM didn’t have a particularly large number of Chamber plurality seats to begin with. Moreover, in 2015 Mexico’s Federal Judiciary Electoral Tribunal (TEPJF) ruled that parties could nominate candidates from a different political party, provided the parties had a coalition agreement. On the other hand, the stratagem pursued in 2018 by the “Juntos Haremos Historia” (JHH; “Together We’ll Make History”) coalition of the National Regeneration Movement (MORENA), the Workers’ Party (PT) and the Social Encounter Party (PES) was anything but limited. For the Chamber of Deputies, the three parties ran together in 292 of Mexico’s 300 congressional districts, but in the coalition agreement 142 nominations were assigned to MORENA, and 75 each to PT and PES.

To be certain, it is not unusual for smaller parties like PT and PES to have a disproportionate share of single-member nominations in mixed-member majoritarian systems which allow party coalitions: in a nutshell, larger parties often bow to smaller parties’ demands, outrageous as they may be, if that is what it takes to avoid the risk of losing elections. That said, giving away half the Chamber’s single-member seat nominations to a couple of very small parties came across as both extreme and highly suspicious, all the more so considering that for the Mexican Senate plurality races, JHH nominated 49 candidates from MORENA, but only eight from PES and five from PT. However, unlike in the Chamber of Deputies, there is no eight percent cap in place for the distribution of Senate PR seats, and therefore MORENA gained nothing from giving away upper house plurality nominations to its much smaller allies.

JHH went on to score a landslide victory in the general election last July, securing an absolute majority for its presidential candidate Andrés Manuel López Obrador (better known by his initials AMLO), as well as a sizable plurality in the legislative election. In the Chamber of Deputies, final results show JHH won 220 of 300 plurality seats (including eight mandates won by MORENA running alone), with the following results for its constituent parties:

Party % (Votes) Seats % (Seats)
MORENA 37.2 106 35.3
PT 3.9 58 19.3
PES 2.4 56 18.7
JHH Total 43.5 220 73.3

The sole beneficiaries of the victorious coalition’s over-representation in the plurality component were PT and PES, as MORENA ended up slightly under-represented. Again, while it is not unusual for smaller parties within larger coalitions in mixed-member majoritarian systems to have a share of seats in excess of their percentage of the vote (even without considering the PR component), this was nonetheless a truly extreme outcome. By comparison, the Senate election had a more typical plurality outcome, as shown below:

Party % (Votes) Seats % (Seats)
MORENA 37.4 42 43.8
PT 3.8 5 5.2
PES 2.3 8 8.3
JHH Total 43.6 55 57.3

(JHH’s smaller majority of upper house plurality seats was due to the fact that unlike in the Chamber of Deputies, Senate plurality mandates are allocated on the basis of two seats for the winning ticket and one for the first runner-up in each one of Mexico’s thirty-two federal entities).

For the distribution of Chamber PR seats, MORENA received 41.34% of the effective vote, so it could have no more than 49.34% of the 500 Chamber seats, which translated to 246 seats. However, after the initial allocation of PR mandates MORENA had a total of 188 seats (106 plurality and 82 list), well below its corresponding maximum seat total. On the other hand, PT, with 4.36% of the effective vote, would have been entitled to nine list seats, but unexpectedly exceeded its 12.36% cap, or 61 seats due to the party’s large number of plurality victories; PES fell below the three percent valid vote minimum required to take part in the distribution of PR seats. Consequently, PT’s list seat total was reduced to three mandates, and the remaining 197 PR seats were distributed among the other six qualifying parties. In all, JHH won 308 of 500 Chamber seats, as detailed below:

Party FPTP PR Total % (Total)
MORENA 106 85 191 38.2
PT 58 3 61 12.2
PES 56 0 56 11.2
JHH Total 220 88 308 61.6

Mexico’s National Electoral Institute’s General Council Agreement INE/CG1181/2018 [PDF] details the official distribution of Chamber of Deputies PR list mandates in Mexico’s 2018 federal election, while Federal Elections in Mexico has nationwide- and federal entity-level results of elections in Mexico since 1997.

Although the eight percent cap deprived PT of just six seats, this left several of its leaders without a seat in the Chamber of Deputies, and the party went to court to have the result overturned. To that end, PT actually admitted some of its successful plurality candidates weren’t really party members after all, and sought a judicial review of JHH’s officially registered coalition agreement. However, the court rejected what it correctly perceived as a transparent attempt by PT to re-structure the previously agreed distribution of Chamber plurality nominations, in order to bypass the eight percent cap and increase its number of list mandates. In essence, TEPJF ruled JHH’s coalition agreement was a done deal which could no longer be altered after the election had been carried out with the agreement in place, and for good measure reaffirmed its earlier 2015 ruling that parties could nominate candidates from a different political party, provided the parties had a coalition agreement.

Just as important, TEPJF ruled that under the prevailing legal and constitutional arrangements, it was not possible to consider JHH’s coalition performance as if it were a single party for the purposes of determining over-representation, as it would run counter to the requirement such determination must be carried out on an individual party basis. Had Chamber seats been allocated among coalitions (and had all three major coalitions been in place in every congressional district, as was the case with the presidential election), JHH’s seat total would have been limited to 269 mandates – a significantly reduced yet nonetheless substantial majority.

TEPJF also confirmed that PT exceeded the eight percent cap by six seats (because 12.36% of 500 seats equals 61.8 seats, it was argued the party went above the cap by 5.2 seats (67 minus 61.8), which should have rounded down to five seats; however, this argument was rejected on the grounds that with 62 seats of 500 – 12.4% of the total – PT would have had a disparity gap of 8.04%, a figure just above the eight percent maximum).  The court ruled as well that JHH’s plurality victories could not be assigned to MORENA on account of the fact that the party contributed the vast majority of votes to that end.

(MORENA outpolled both PT and PES in every congressional district, and even if the party had run alone it would have secured a large majority of plurality seats, while PT and PES would have won none. However, in such hypothetical scenarios – which assume an identical distribution of votes among the parties contesting the 2018 federal election – MORENA’s Chamber of Deputies seat total would have been limited to 246 mandates by the eight percent cap, while PT would have received no more than 13 list mandates and PES would have had no seats, leaving MORENA and PT with a relatively slender joint majority in the Chamber.)

Nevertheless, TEPJF’s rulings on some of these controversies were not unanimous. Judge Felipe de la Mata Pizaña wrote a concurring opinion calling for the current implementation of the eight percent cap provision to be reconsidered for future elections, while Judge Reyes Rodríguez Mondragón issued an extensive dissenting opinion, in which he argued that the actual party affiliation of plurality winners should be taken into account for determining the eight percent cap during the distribution of PR seats. Notably, the dissent cites a number of political science scholarly sources, including both the Spanish-language edition of “Presidents and the Party System” (edited by S. Mainwaring and M.S. Shugart) and “Seats and Votes” by R. Taagepera and M.S. Shugart, even carrying out the calculations to determine the effective number of parties index for Mexico.

(For further information, please refer to TEPJF’s rulings on SUP-JDC-0429-2018; SUP-JDC-0438-2018SUP-JDC-0444-2018SUP-REC-0934-2018; and SUP-REC-0943-2018 [PDF].)

However, beyond the practical difficulties entailed by implementing this approach, it is not clear that it would have resulted in a significantly different distribution of seats. After Mexico’s newly elected legislators were sworn in just over three months ago, a large number of JHH’s 220 plurality deputies ostensibly elected as members of PT or PES joined MORENA’s parliamentary group, as shown below:

Party Elected Group Gain/Loss
MORENA 106 162 +56
PT 58 28 -30
PES 56 30 -26

Had the eight percent cap been calculated on the basis of parliamentary group affiliation figures, the initial distribution of PR list seats, which as previously noted granted nine mandates to PT and 82 to MORENA would have been definitive, as neither party would have reached its eight percent-capped seat total. Moreover – and quite ironically – JHH would have obtained an even larger Chamber majority of 311 seats (of which 244 seats would have gone to MORENA, 37 to PT and 30 to PES).

In conclusion, while PT and PES contributed very little in terms of votes to JHH’s sweeping victory in the 2018 federal election, the gaming of the eight percent disparity cap through the assignment of a disproportionately large number of plurality nominations to these parties allowed the coalition to obtain a much larger majority in the Chamber of Deputies than it could have otherwise attained. Even so, the triumphant coalition parties overplayed their hand, and the stratagem backfired on PT; this in turn led to a public disclosure of the scheme’s existence (already highly suspected, not least because it was largely absent in the Senate election, which has no disparity cap provisions), as part of an unsuccessful effort to have the unexpected adverse outcome reversed in court.

Even though a majority of Mexico’s Federal Judiciary Electoral Tribunal justices have reaffirmed the validity of electoral provisions which allow outcomes like these, it seems an obvious flaw in the design of the system that parties can run in alliances, but the caps on over-representation are calculated at the individual party level, as pointed out by Dr. Matthew Shugart himself on this blog shortly after the 2018 federal election took place. Moreover, the gaming of the eight percent disparity cap in the 2018 federal election effectively altered the nature of the Chamber of Deputies electoral system, causing it to function almost like a parallel system, in which the outcome of plurality races had very little impact in the distribution of party list seats. That may not appear to be cause for excessive concern in the here and now, given that JHH would have in all likelihood secured a majority of Chamber seats even if the coalition hadn’t gamed the eight percent disparity cap, but the issue could have wider ramifications with unpredictable consequences in the years to come. 

IRV-MMP

What do folks think of this idea, proposed by Mark Roth in the thread on open-list MMP?

I do not believe it is entirely necessary to have two votes; though I don’t oppose the idea. Essentially I would have IRV-MMP. An instant runoff determines which candidate wins the local seat in each district. First preferences determine who receives the at-large seats. If a voter wants the Greens, but knows that they won’t win locally, a vote 1 Greens 2 Labor has the effect of supporting a winnable local candidate and helping the Greens secure seats in general. I would allow transfers to second (or lower) ranked parties should the first choice(s) of parties not reach a threshold. I would also be inclined to allow a List Party that isn’t running a candidate to appear on the ballot anyway; probably marked to indicate that the List cannot win the local seat. The candidates who lose in their local race would be selected to fill the at-large seats based on their personal vote counts. List order would only be a tiebreaker.

Decoy lists would technically be possible, but they would stick out like a sore thumb, require voter coordination to ensure that the “right” candidate gets the vote in the district level races, and would still need to front candidates in local races to have enough warm bodies.

As I say at the other thread in a comment of my own, I like it much better than the “AV+” idea of having two votes (one ranked-choice for local candidates and the other for list).

Is rural-urban PR gaining on MMP?

In the British Columbia mail-in referendum, the most likely option to win, should change from FPTP be endorsed, has seemed to be Mixed-Member Proportional (MMP). However, a poll from Mainstream BC, released on Nov. 8, suggests that one of the other options could be gaining.

The one that looks close, at least in this poll, is Rural-Urban PR (RUP). I reviewed all of the proposals before, and so will only briefly describe the RUP system here: It would be Single Transferable Vote (STV) for most of the province, but MMP in rural areas. The proposal is meant to address concerns that rural districts (ridings) would have to be too large if STV were used in the entire province, while still giving the rural interior a reasonable degree of proportionality.

This poll shows that on the critical first question, whether to keep FPTP or move to PR, the BC Interior prefers the status quo, 53.3% to 46.7%. Metro Vancouver voters only narrowly favor PR (50.1%), while Vancouver Island favors PR by a slightly wider margin (52.7%). The regional samples are small, so should be treated with caution. Nonetheless, they are suggestive of skepticism of PR in rural areas, exactly what the RUP proposal is meant to address. Overall, it is way too close to call: 50.5% for keeping FPTP, 49.9% for PR.

It is on preference over PR systems that we see the most interesting divide. According to this poll, MMP leads by a wide margin in Metro Vancouver: 50.4% to 32.2% for RUP and 17.4% for the third option, Dual-Member PR (DMP). On Vancouver Island, it is similar, but tighter: 40.4%, 38.3%, 21.3% (this is just 86 respondents). In BC Interior, however, the poll gets RUP on 49.5%, then MMP 37%, and DMP just 13.5%.

Overall, this still puts MMP in front, given the greater population of Vancouver: 44.8%, 38.2%, 17.0%.

It could be that RUP is gaining, as earlier polls had it and DMP both far behind MMP. There is an on-line presence for a specifically pro-RUP effort (“YUP for RUP”). There is some expressed support for RUP, for instance by Andrew Coyne in the National Post. He says he favors it “mostly for the STV part.”

It would be very interesting if RUP ended up winning, but on the strength of rural voters who, were it chosen, would vote by MMP, while Vancouver voters (who would vote by STV) had majority-preferred MMP but would get STV. OK, that was convoluted, but that is the point. It is not a likely outcome, but it is at least possible, provided it is really close in Vancouver and there is a decisive turn towards RUP in rural areas. And would be interesting!

The choice of PR model, if PR defeats FPTP in the first question, will be determined by province-wide alternative vote (the second question is a ranked ballot). So, it would be good to know what DMP supporters’ second choice tends to be. I would guess MMP, but that is just that–a guess. It probably depends on which feature of DMP that minority likes best–all members elected in local districts (for which STV would seem to beat MMP) or province-wide proportionality (for which MMP is clearly better than RUP).

A final note from the poll: It has 963 total respondents, but only 440 for the second question. So lots of voters may be planning to skip the question on choice of models. It is unclear whether that is because those who want FPTP are not weighing in at all, or because of pro-PR canvassers saying things like “if you are confused about the second part, you can skip it” (which I heard in my brief observation of campaigning).

Correction on BC’s MMP proposal

I realized only today that I had misread the proposal for the Mixed-Member Proportional (MMP) system in the British Columbia Attorney General’s report on the options. [Or maybe not, after all: See Wilf’s comment.]

I had thought the compensation would play out only in regions, as is the case in Scotland. I based this on the phrase in the report that says, “the List PR seats are allocated on a regional basis rather than a province-wide basis.” However, somehow I missed the clear statement in the preceding paragraph of the report, where it says, “The overall share of seats each party holds in the Legislative Assembly is determined by the party’s share of the province-wide vote it receives.”

In other words, the regions would affect only which specific candidates are seated from the compensatory (“top-up”) lists, and thus the regional balance of each party’s caucus. They would not affect the number of such seats a party wins overall.

The provision also makes workable the possible open list, which is given as an option to be worked out post-referendum, but which the Premier has said he will ensure is chosen rather than a closed list. If the lists were province-wide, open lists would make for more cumbersome ballots and arguably excess choice (as well as failing to ensure regional balance in the assembly).

The details of how one balances province-wide proportionality with open regional lists are complex. It is the system in Bavaria, however, so it is not unproven.

I have corrected my two previous entries on this accordingly:

1. BC electoral reform options for referendum

2. What can we expect from electoral reform in BC?