Quoted in 538 article about House size

Very pleased with this article by Geoffrey Skelley at FiveThirtyEight: “How The House Got Stuck at 435 Seats.” The author interviewed me for the piece, and references my work and that of coauthors, including Rein Taagepera, the discoverer of the cube root law of assembly size.

There is also a good visualization tool for how each state would be over- or under-represented with various House sizes.

Indian assembly size to double, and then some?

Is the Indian Lok Sabha about to be more than doubled in size? There is this paragraph in an article in The Wire by Madhav Godbole otherwise about the role of parliament and its committees in India’s Covid-19 response:

In mature democracies, the efficacy of parliament largely depends on the functioning of its committees. I have been consistently advocating the strengthening of parliamentary committees. The importance of these committees will be all the more after the impending delimitation of Lok Sabha constituencies and an increase in the estimated strength of Lok Sabha to 1,200 members and of Rajya Sabha to 800 members. This is the ostensible reason for the construction of a new parliament building at such a break-neck speed even during the current pandemic. But, this will be futile unless parliament is permitted to function and does not become just an appendage of governance structure.

That size of the Lok Sabha would slightly overshoot the cube root law’s expectation for a country of about 1.3 billion, although it would certainly be closer to the cube root of population than the current 543 members. The current size is about half the cube root (which would be around 1,090), while the proposed expanded assembly would be about 1.10 times the cube root.

I’ve asked before the question of whether there is a tradeoff at some point where an assembly gets too large to be functional, even if it is consistent with the cube root. I have no idea where that point might be. The cube root law itself is based on a balance between two types of “communication channel”–those between representatives and their constituents and those among members themselves. Large countries should have large assemblies, and India currently has a very small assembly for country size.

One thing is for sure, there can be a lot more committees and subcommittees, or else larger committees, if the Lok Sabha is made this large. I don’t think we have a good theory of how committee structure relates to either assembly size or population. Moreover, this is a separate question from how “strong” a committee system is, as the quote from Godbole attests to.

Also it should be noted that this proposed new size for the second chamber, the Rajya Sabha, is quite excessive.

(Thanks to Patrick G on Twitter for the tip.)

Chamber size and party ‘strength’

What do folks think the correct answer to this question is: How does the size of an assembly affect the strength of political parties?

By strength, I mean the relative freedom of the individual member to cultivate constituency ties and to dissent from party leadership on votes on legislation. I also mean, holding other factors constant.

Suppose a country’s assembly is significantly smaller than its expected size, per the cube-root law. If nothing else changes, how would raising the size be expected to affect the strength of parties?

Obviously, I am thinking about potentially expanding the US House, so a starting point of non-hierarchical parties, and only two of them (and presidentialism, etc.). But I am interested in the question more broadly, and whether features of US party and legislative politics, aside from the small House size, change the impact of increased size on party strength in a manner that might be different from how it would play out in other contexts.

I ask because I genuinely do not know. I could see it going either way. A larger house, for a given population, means each member represents fewer voters, obviously. This could make personal-vote and constituency-service strategies more viable, thereby in some sense making parties “weaker”. On the other hand, a larger assembly (here, independent of population) makes internal collective action more challenging. This could result in members delegating (or simply losing) more authority to internal party leadership, making parties “stronger.” Note that these possible directions of change are closely connected to the two factors that go into the cube root law itself–this is a logical model that is based on balancing (and minimizing overall) two types of “communication channels”: those between legislators and constituents, and those among legislators themselves.

It is possible both directions of change can happen at the same time, implying parties get weaker in some ways and stronger in others. That is, more constituency-oriented behavior, but also more party leadership control over votes and especially over speaking time. I am not sure what that means for overall strength. Maybe that isn’t even the right way to frame the question; skepticism over my own question framing is why I use the inverted commas in the title of this post.

Finally, theoretically and all else equal, a larger assembly means more parties should be represented (per the Seat Product Model). I have my doubts that this would be realized in the US, however, given all the other barriers to third-party representation. Unless the House were truly huge, I do not expect much impact there as long as it is elected in single-seat districts, and with primaries (or with “top two” or even “top four” or five). However, parties’ internal strength could be affected. But which way?

US House size increase: Inherently valuable?

We have frequently discussed here the question of the size of the US House. As regular readers will know, the House is undersized, relative to the cube root law, under which an assembly is expected to be approximately the cube root of the population. The law is both theoretical (grounded in a logical model) and quite strong empirically (see the graph posted years ago). However, the US House is far smaller than the cube root predicts, which would be somewhere north of 600. In fact, the House has been fixed at 435 for more than a century,1 even as the population has grown greatly.

So there is a good political science case to be made for expanding House size. My question here is whether expanding the House is something that reformers should pursue for its own sake. Or is it of subordinate value?

I ask because many advocates of a move to proportional representation (PR) will tend to believe that PR would work better in a larger House. The larger the House, the fewer states there are with only one Representative, wherein obviously a plurality or majority system remains the only option.

Strategically, however, it could be a mistake for the PR movement to hitch its wagon to the House expansion movement. If PR is attached to the idea of “more politicians” it is probably in a lot of trouble. Advocates for democracy reform might prefer both a larger House and PR, but wouldn’t most of us prefer PR to a larger House, if we can have only one or the other? (Perhaps I will engage in blasphemy, but I might trade off a somewhat smaller House if it were necessary to get PR. In other words, I value PR ahead of almost any reform I can imagine.)

Another way to look at this is, would the reformist “capital” spent on getting a larger House be worth it if we ended up with 650 single-seat districts instead of 435? I have my doubts.

While a larger House should result in more parties represented, independent of the electoral system, I am not sure I believe that we would see it under otherwise existing US political and institutional conditions. As I’ve noted many times, the Seat Product Model says that the US “should” have a party system with more than two parties, and the largest one averaging around 47% of the seats, instead of our actual average which is obviously greater than 50%. It should have an effective number of seat-winning parties of about 2.75, even with 435 seats. With 650, the expectation rises to 2.94 (and a largest averaging just under 45% of the seats). In the real USA where there are really only two parties, and we keep single-seat districts, do we have any reason to believe just adding about 200 seats (let alone a more realistic 100 or so) would result in any increase in representation of other parties? I doubt it.

So, why bother? Is the value of a smaller number of people per Representative so strong that we want it regardless of how the party system pans out? I worry it actually could have a deleterious effect. Other things equal, more seats means more homogenous districts. Some of those could be minority districts that can’t now be drawn (given other criteria in district line-drawing) and, of course, those minorities in theory could be minority-party supporters as well as nonpartisan minorities (racial and ethnic, etc.). The latter is valuable, of course. But a concern is that in an existing and likely persistent two-party system that you simply end up with more safe seats (Brian Frederick notes this possibility in his book on US House size, even as he argues in favor of an increased size). We have plenty of safe seats already! If we had multiparty politics to start with, I think a larger House would help smaller parties win more seats, and possibly render districts on average more competitive. But in a two-party system, I think it makes districts on average less competitive. (I am not sure about this, so discuss away in the comments!) As for racial and ethnic minorities, I am skeptical that we get enough of a boost from a larger number of single-seat districts to make the tradeoffs in less competitive elections worth it. They’d be better represented by PR anyway, obviously.

Bottom line: With so many reformist needs in US democracy, I don’t think House size is worth pursuing, unless it can be in a package that gets us PR. It certainly should not be allowed to be the poison pill that prevents getting PR, as I fear it could be, were we ever otherwise in a place where PR was a live option.

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  1. Except for temporary increases to accommodate Alaska and Hawaii; at the next census and reapportionment, it reverted to 435.

Italy assembly-size reduction: Cube root!

Based on the results of a referendum, Italy will be changing the size of its Chamber of Deputies from 630 to 400. By the cube root law (Taagepera, 1972) a country the size of Italy (around 60.5 million) should have about 392 seats in its first chamber. I’d say 400 is “about 392” and so this outcome is an obviously good thing.

Thanks to Matthew Bergman, Miroslav Nemčok, and Rein Taagepera for calling this to my attention. Rein also sent along an Italian newspaper article (PDF, a bit blurry) in which he was quoted.

The assembly reduction proposal was advanced by the Five Star Movement. As Rein said in personal communication, “sometimes populists get it right.”

Also, the Italian Senate is being reduced, to 200 (from 315, not counting appointed senators). I am not aware of any predictive model for how large a given second chamber “should be”, at least in unitary systems, but I note that in A Different Democracy, 2014, p. 214, we report that the mean second chamber in a unitary state is 0.53 times the size of the first chamber. So Italy is continuing to follow this pattern.

NYT endorses a larger House, with STV

Something I never thought I would see: The editorial board of one of the most important newspapers in the United States has published two separate editorials, one endorsing an increase in the size of the House of Representatives (suggesting 593 seats) and another endorsing the single transferable vote (STV) form of proportional representation for the House.

It is very exciting that the New York Times has printed these editorials promoting significant institutional reforms that would vastly improve the representativeness of the US House of Representatives.

The first is an idea originally proposed around 50 years ago by my graduate mentor and frequent coauthor, Rein Taagepera, based on his scientific research that resulted in the cube root law of assembly size. The NYT applies this rather oddly to both chambers, then subtracts 100 from the cube root result. But this is not something I will quibble with. Even an increase to 550 or 500 would be well worth doing, while going to almost 700 is likely too much, the cube root notwithstanding.

The second idea goes back to the 19th century (see Thomas Hare and Henry R. Droop) but is as fresh and valid an idea today as it was then. The NYT refers to it as “ranked choice voting in multimember districts” and I have no problem whatsoever with that branding. In fact, I think it is smart.

Both ideas could be adopted separately, but reinforce each other if done jointly.

They are not radical reforms, and they are not partisan reforms (even though we all know that one party will resist them tooth and nail and the other isn’t exactly going to jump on them any time soon). They are sensible reforms that would bring US democracy into the 21st century, or at least into the 20th.

And, yes, we need to reform the Senate and presidential elections, too. But those are other conversations…

Economix: Expand the US House

It is good to see the undersized nature of the US House of Representatives get attention in the New York Times‘s Economix blog. The author is Bruce Bartlett, who “held senior policy roles in the Reagan and George H.W. Bush administrations and served on the staffs of Representatives Jack Kemp and Ron Paul”.

Bartlett notes that,

according to the Inter-Parliamentary Union, the House of Representatives is on the very high side of population per representative at 729,000. The population per member in the lower house of other major countries is considerably smaller: Britain and Italy, 97,000; Canada and France, 114,000; Germany, 135,000; Australia, 147,000; and Japan, 265,000.

The strongest empirical relationship of which I am aware between population size and assembly size is the cube root law. Backed by a theoretical model, it was originally proposed by Rein Taagepera in the 1970s. A nation’s assembly tends to be about the cube root of its population, as shown in this graph.*

Fig 7.1

Note the flat line for the USA, indicating lack of increase in House size, since the population was less than a third what it is today. This recent static period is in contrast to earlier times, depicted by the zig-zag black line, in which the USA regularly adjusted House size, keeping it reasonably close to the cube-root expectation.

At only about two thirds of the cube-root value of the population (as of 2010 census), the current US House is indeed one of the world’s most undersized. However, there are some even more deviant cases. Taking actual size over expected size (from cube root) , the USA has the seventh most undersized first or sole chamber among thirty-one democracies in my comparison set. The seven are:

    .466 Colombia
    .469 Chile
    .518 India
    .538 Australia
    .590 Netherlands
    .614 Israel
    .659 USA

As expected, the mean ratio for the thirty-one countries is very close to one (0.992, with a standard deviation of .37). The five most oversized, all greater than 1.4, are France, Germany, UK (at 1.67), Sweden, and Hungary. (The latter was at a whopping 1.80, but has since sharply reduced its assembly size.) Spain, Denmark, Switzerland, Portugal, and Mexico all get the cube root prize for having assembly sizes from .975 to 1.03 of the expectation.

One thing I did not know is that an amendment to the original US constitution was proposed by Madison. According to Bartlett, it read:

After the first enumeration required by the first article of the Constitution, there shall be one representative for every 30,000, until the number shall amount to 100, after which the proportion shall be so regulated by Congress, that there shall be not less than 100 representatives, nor less than one representative for every 40,000 persons, until the number of representatives shall amount to 200; after which the proportion shall be so regulated by Congress, that there shall not be less than 200 representatives, nor more than one representative for every 50,000 persons.

Obviously, Madison’s formula would have run into some excessive size issues over time. And Bartlett does not suggest how much the House should be increased, only noting that its ratio of one Representative for very 729,000 people is excessive. On the other hand, Madison’s ratio of one per 50,000 would produce an absurdly large House! It is just the need to balance the citizen-representative ratio with the need for representatives to be able to communicate effectively with one another that Taagepera devised the model of the cube root, which as we have seen, fits actual legislatures very well.

The cube root rule says the USA “should have” a House of around 660 members today, which would remain a workable size. (If the USA and UK swapped houses, each would be at just about the “right” size!) Even an increase to just 530 would put it within about 80% of the cube root.

As Bartlett notes, at some point the US House will be in violation of the principle of one person, one vote (due to the mandatory representative for each state, no matter how small). However, a case filed in 2009 went nowhere.



* Each country is plotted according to its population, P (in millions), and the size, S, of its assembly. In addition, the size of the US House is plotted against US population at each decennial census from 1830 to 2010.
The solid diagonal line corresponds to the “cube root rule”: S=P^(1/3).
The dashed lines correspond to the cube root of twice or half the actual population, i.e. S=(2P)^(1/3) and S=(.5P)^(1/3).

A variant of the graph will be included in Steven L. Taylor, Matthew S. Shugart, Arend Lijphart, and Bernard Grofman, A Different Democracy (Yale University Press).

An even earlier version of the graph was posted here at F&V in 2005.

Citations are always nice–Increasing the size of the US House

David Fredosso, writing at Conservative Intelligence Briefing, makes the case for increasing the size of the US House, citing one of my previous posts advocating the same. He makes two additional and valuable points: (1) “The Wyoming Rule”, by which the standard Representative-to-population ratio would be that of the smallest entitled unit, is misleading as to how representation is currently (mal-)apportioned; (2) Increasing the size of the House would not, as is sometimes assumed, be of benefit to Democrats and liberals.

David quibbles with the Wyoming part of the story, noting that “Wyoming is not the most overrepresented state — by a long way, that distinction goes to Rhode Island, with its two districts, average population 528,000”, whereas Wyoming has a population of 568,000 (and one seat).

I would note that this is a very small quibble indeed, as the Wyoming Rule–which, to be fair, I neither named nor invented–refers to “smallest entitled unit” not to “most over-represented unit”. Of course, every state is a unit entitled to at least one, but sometimes a state with two members indeed will be over-represented to a greater degree than some state with one member. Whichever we base it on–smallest entitled or most over-represented–the principle is the same: expand the House.

David proposes a House of 535, and has a table of how that would change each state’s current representation. I would go higher (600 or so), but the precise degree of increase is an even smaller quibble. I am pleased to see this idea being promoted in conservative (or liberal, or whatever) circles. And it’s always nice to be cited.

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See also:

Reapportionment–a better way?; this includes a discussion of the cube-root rule of assembly size, and a graph of how the US relationship of House size to population compares to that of several other countries, and how it has changed over time as the US population has grown, but the House stopped doing so.

US House size, continued

Spurious majorities in the US House in Comparative Perspective

In the week since the US elections, several sources have suggested that there was a spurious majority in the House, with the Democratic Party winning a majority–or more likely, a plurality–of the votes, despite the Republican Party having held its majority of the seats.

It is not the first time there has been a spurious majority in the US House, but it is quite likely that this one is getting more attention ((For instance, Think Progress.)) than those in the past, presumably because of the greater salience now of national partisan identities.

Ballot Access News lists three other cases over the past 100 years: 1914, 1942, and 1952. Sources disagree, but there may have been one other between 1952 and 2012. Data I compiled some years ago showed a spurious majority in 1996, if we go by The Clerk of the House. However, if we go by the Federal Election Commission, we had one in 2000, but not in 1996. And I understand that Vital Statistics on Congress shows no such event in either 1996 or 2000. A post at The Monkey Cage cites political scientist Matthew Green as including 1996 (but not 2000) among the cases.

Normally, in democracies, we more or less know how many votes each party gets. In fact, it’s all over the news media on election night and thereafter. But the USA is different. “Exceptional,” some say. In any case, I am going to go with the figure of five spurious majorities in the past century: 1914, 1942, 1952, 2012, plus 1996 (and we will assume 2000 was not one).

How does the rate of five (or, if you like, four) spurious majorities in 50 elections compare with the wider world of plurality elections? I certainly do not claim to have the universe of plurality elections at my fingertips. However, I did collect a dataset of 210 plurality elections–not including the USA–for a book chapter some years ago, ((Matthew Soberg Shugart, “Inherent and Contingent Factors in Reform Initiation in Plurality Systems,” in To Keep or Change First Past the Post, ed. By André Blais. Oxford: Oxford University Press, 2008.)) so we have a good basis of comparison.

Out of 210 elections, there are 10 cases of the second party in votes winning a majority of seats. There are another 9 cases of reversals of the leading parties, but where no one won over 50% of seats. So reversals leading to spurious majority are 4.8% of all these elections; including minority situations reversals are 9%. The US rate would be 10%, apparently.

But in theory, a reversal should be much less common with only two parties of any significance. Sure enough: the mean effective number (N) of seat-winning parties in the spurious majorities in my data is just under 2.5, with only one under 2.2 (Belize, 1993, N=2.003, in case you were wondering). So the incidence in the US is indeed high–given that N by seats has never been higher than 2.08 in US elections since 1914, ((The original version of this statement, that “N is almost never more than 2.2 here” rather exaggerated House fragmentation!)) and that even without this N restriction, the rate of spurious majorities in the US is still higher than in my dataset overall.

I might also note that a spurious majority should be rare with large assembly size (S). While the US assembly is small for the country’s population–well below what the cube-root law would suggest–it is still large in absolute sense. Indeed, no spurious majority in my dataset of national and subnational elections from parliamentary systems has happened with S>125!

So, put in comparative context, the US House exhibits an unusually high rate of spurious majorities! Yes, evidently the USA is exceptional. ((Spurious majorities are even more common in the Senate, where no Republican seat majority since at least 1952 has been based on a plurality of votes cast. But that is another story.))

As to why this would happen, some of the popular commentary is focusing on gerrymandering (the politically biased delimitation of districts). This is quite likely part of the story, particularly in some sates. ((For instance, see the map of Pennsylvania at the Think Progress link in the first footnote.))

However, one does not need gerrymandering to get a spurious majority. As political scientists Jowei Chen and Jonathan Rodden have pointed out (PDF), there can be an “unintentional gerrymander,” too, which results when one party has its votes less optimally distributed than the other. The plurality system, in single-seat districts, does not tote up party votes and then allocate seats in the aggregate. It only matters in how many of those districts you had the lead–of at least one vote. Thus a party that runs up big margins in some of its districts will tend to augment its total in its “votes” column at a faster rate than it augments its total in the “seats” column. This is quite likely the problem Democrats face, which would have contributed to its losing the seat majority despite its (apparent) plurality of the votes.

Consider the following graph, which shows the distribution (via kernel densities) of vote percentages for the winning candidates of each major party in 2008 and 2010.

Kernel density winning votes 2008-10
Click image for larger version

We see that in the 2008 concurrent election, the Democrats (solid blue curve) have a very long and higher tail of the distribution in the 70%-100% range. In other words, compared to Republicans the same year, they had more districts in which they “wasted” votes by accumulating many more in the district than needed to win it. Republicans, by contrast, tended that year to win more of their races by relatively tighter margins–though their peak is still around 60%, not 50%. I want to stress, the point here is not to suggest that 2008 saw a spurious majority. It did not. Rather, the point is that even in a year when Democrats won both the vote plurality and seat majority, they had a less-than optimal distribution, in the sense of being more likely to win by big margins than were Republicans.

Now, compare the 2010 midterm election, in which Republicans won a majority of seats (and at least a plurality of votes). Note how the Republican (dashed red) distribution becomes relatively bimodal. Their main peak shifts right (in more ways than one!) as they accumulate more votes in already safe seats, but they develop a secondary peak right around 50%, allowing them to pick up many seats narrowly. That the peak for winning Democrats’ votes moved so much closer to 50% suggests how much worse the “shellacking” could have been! Yet even in the 2010 election, the tail on the safe-seats side of the distribution still shows more Democratic votes wasted in ultra-safe seats than is the case for Republicans. ((It is interesting to note that 2010 was very rare in not having any districts uncontested by either major party.))

I look forward to producing a similar graph for the 2012 winners’ distribution, but will await more complete results. A lot of ballots remain to be counted and certified. The completed count is not likely to reverse the Democrats’ plurality of the vote, however.

Given higher Democratic turnout in the concurrent election of 2012 than in the 2010 midterm election, it is likely that the distributions will look more like 2008 than like 2010, except with the Republicans retaining enough of those relatively close wins to have held on to their seat majority.

Finally, a pet peeve, and a plea to my fellow political scientists: Let’s not pretend there are only two parties in America. Since 1990, it has become uncommon, actually, for one party to win more than half the House votes. Yet my colleagues who study US elections and Congress continue to speak of “majority”, by which they mean more than half the mythical “two-party vote”. In fact, in 1992 and every election from 1996 through at least 2004, neither major party won 50% of the House votes. I have not ever aggregated the 2006 vote. In 2008, Democrats won 54.2% of the House vote, Republicans 43.1%, and “others” 2.7%. I am not sure about 2010 or 2012. It is striking, however, that the last election of the Democratic House majority and all the 1995-2007 period of Republican majorities, except for the first election in that sequence (1994), saw third-party or independent votes high enough that neither party was winning half the votes.

Assuming spurious majorities are not a “good” thing, what could we do about it? Democrats, if they are developing a systematic tendency to be victims of the “unintentional gerrymander”, would have an objective interest in some sort of proportional representation system–perhaps even as much as that unrepresented “other” vote would have.

Netherlands assembly size issue?

On a “how to vote” application for the upcoming Dutch election, the second statement you are asked to agree or disagree with is:

The number of members in the Lower House should remain at 150.

Is the size of the chamber an issue in the Netherlands?

For the record, the chamber is one of the most undersized among the major democracies (see graph), according to the cube-root rule.

On a somewhat related note, can anyone explain the Central Planning Agency, mentioned in a Monkey Cage post as an “authoritative” institution that “runs each party’s submissions [i.e. campaign proposals] through a model and offers projections”?

Puerto Rico assembly-size referendum

Via Manuel Álvarez-Rivera:

Voters in Puerto Rico go to the polls next Sunday, August 19, 2012, to cast ballots in a constitutional amendments referendum, concerning the Legislative Assembly’s number of members and the right to bail.

The constitutional amendment on the Legislative Assembly’s number of members proposes a reduction of the number of senators from 27 to 17, and the number of representatives from 51 to 39, starting in 2016. The number of Senate districts would be increased from eight to eleven, but each Senate district would elect one senator, instead of two. In addition, each Senate district would include three House of Representatives districts (instead of five), for a total of 33 House districts; each House district would continue to elect one representative. Moreover, the number of at-large seats in each House would be reduced from eleven to six. Likewise, the minority party representation cap would be reduced from nine to six seats in the Senate, and from 17 to 13 seats in the House of Representatives.

If we go by the cube-root rule, which suggests assembly size tends to be near the cube root of the population, the current first-chamber size of 51 is already only about one third of expected. If this referendum passes, Puerto Rico will have an extremely undersized assembly.

There is some tendency for islands (especially in the Caribbean) to have undersized assemblies. And the cube root rule might not apply to assemblies of not fully sovereign entities (though its underlying theory makes no such explicit claims). In any case, this would be a really small legislature for a “Commonwealth” of around 3.7 million.

Jamaica 2011: As good as PR–or not (updated)

Final results show the PNP won with 53.3% of the votes, to the JLP’s 46.6%. However, even as the final vote total was much closer than the preliminary result upon which this entry was based, the PNP picked up an additional seat. (Note that this gives it exactly two thirds of the seats.)

Thus the result was far from proportional, after all. In fact, it was even more majoritarian than a “typical” FPTP result would be with the given input parameters. The PNP’s Advantage Ratio is 1.25, whereas the Seat-Vote Equation would predict it to have been 1.14.

I am leaving the rest of this as originally crafted. The analysis of other elections stands, but that of 2011 would be altered by this new information. Thanks to Jon, in a comment, for the tip.
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Jamaica held its general election on 29 December. Like the other former British territories in the Caribbean, Jamaica elects its parliament by first past the post (plurality) in single-seat districts. Also like other English-speaking Caribbean islands, Jamaica has a parliament that is significantly undersized, given its population. So this makes Jamaica a perfect opportunity to break out our old favorites, the Cube Root Rule of Assembly Size, and the Seat-Vote Equation.

The election result itself saw an alternation in power from the Jamaican Labour Party (JLP) to the Peoples National Party (PNP). Various news reports before the election had said the election was expected to be close. But it was not. The PNP won 41 seats to the JLP’s 22. Thus the JLP was defeated after a single term, which had been its first time in power since its defeat in 1989. (That was a two-term government, although its second term then was tainted by the PNP’s election boycott in 1983.)

The Jamaican case is of some interest to comparative elections specialists because it has an almost perfect two-party system. The two main parties combined for 99.87% of the vote in this election. The PNP won 61.3%.

Only once since 1959 has the third party in a Jamaican election won more than 1% of the vote (NDM, 5.2%, 1997). That makes Jamaica arguably a more “pure” two-party system than its very large neighbor to the north, and probably the biggest country to have a strict two-party system other than that really big one.

So, how did the system perform, in terms of the proportionality of translating votes into seats? We might expect a party winning over 60% of the vote in a first-past-the-post system to be significantly over-represented. The expectation is all the greater given the small size of the parliament, for the country’s population. With a population of around 2.7 million (just over a million voters), the Cube Root Rule would lead us to expect an assembly of more than double its actual size of 63. ((To be fair, they did increase their assembly size. It was only 60 seats from 1976 to 2007!)) Smaller assemblies mean less proportionality, other things constant. They tend to produce very high disproportionality under FPTP.

Yet the PNP’s 41 seats represent 65.1% of the total, hardly at all greater than its 61.3% of the vote.

The Seat-Vote Equation suggests that a “normal” case of about one million voters, 63 seats, and the top two parties at 61% and 38% of the votes would result in a leading party winning 84% of the seats. That would have been 53 seats, to 10 for the JLP.

In the 2011 election, then, Jamaica’s electoral system produced an almost completely proportional result.

This is not a systemic tendency, or if it is, it is a very new one. In fact, the Advantage Ratio (percent votes divided by percent seats) for the largest party in Jamaica had never been below 1.10 before this election (when it dropped to 1.06). Something has been going on in Jamaican elections recently: Every election that was contested by both major parties since 1959 had seen an Advantage Ratio of at least 1.16. Every contested election from 1976 through 1997 saw this ratio be at least 1.33, peaking at 1.50 in 1997, when the PNP won a third consecutive term. Then suddenly it dropped to 1.12 in 2002, when the PNP won a fourth term, in a very close election (50.14% to 49.77%). ((And, in case you are wondering, as I was, I checked: there is only a small relationship in FPTP systems between the top two parties’ difference in votes and the largest party’s advantage ratio. The effect is statistically significant, but the coefficient is around only .007. In any case, the falling ratio in close elections in 2002 and 2007 is consistent with the modeled relationship, but the greater fall in 2011 is most certainly not.))

From looking at the data on seat allocation, I can’t tell what has changed. But I can certainly tell that something has. For the third time in a row, the result has been unusually proportional for a FPTP system–and, in 2011, quite proportional for any electoral system.

The election was called early, as one was not due until the fall of 2012. The Prime Minister, Andrew Holness, in September replaced Bruce Golding (yes, another case of inter-electoral change of PM through “intra-party” mechanisms). Apparently, Holness felt he needed to go to the people for a new mandate. Apparently, it did not work out so well.

As an aside, how often do countries (especially in the Western world) hold elections in the final week of December? I imagine it must be very unusual.

As a further aside, in how many other countries is the more right-wing of the major parties called “Labour”? Or does the more left-wing party have “National” in its name? ((Yes, of course, it also has “People’s”, which is pretty much the only way I can remember which is which.))


Data cited in this entry are from my own research files.

Anomaly Watch: Trinidad and Tobago votes

Campaigning is in the final stages in advance of the Trinidad and Tobago general election of Monday, 24 May. The race is expected to be tight. This is a “snap” election called by PM Patrick Manning, leader of the Peoples National Party (PNM). Will he be sorry for having called it early?

In my work on “systemic failure” and reform in FPTP systems,* I concluded by drawing up a “watch list” of jurisdictions where recent results suggested the electoral system was inherently prone to producing anomalies, based on deviations of actual outcomes from what the Seat-Vote Equation would expect. T&T was on my Watch List. In the case of T&T, the inherent tendency towards unexpected outcomes derives from a frequent over-representation of the second-largest party, relative to expectations based on “normal” performance of FPTP systems.

For instance, in 1995 and 2001, the top two parties tied in seats due to the second party performing considerably better in seats that would be normally expected. In 1995 the PNM was the largest party but it won a lower percentage of seats (47.2%) than of votes (48.8%); in 2001 the United National Congress (UNC) was first in votes by a respectable margin (49.9% to 46.5%) yet each party won half the seats. Either of these elections could have resulted in a spurious majority (or “wrong winner”).

This will be the country’s fifth election since 2000. The 2001 election had been called very early: in 2000 the UNC had won a very narrow majority of both votes and seats (51.7% and 52.7%, respectively). It fell to 49.9% of votes and half the seats in 2001, and then another election was called in 2002. This one produced alternation to the PNM, with majorities of both seats and votes (55.6% 50.9%, respectively). The party was reelected in 2007, and despite a fall in its votes (to 45.9%) its seats increased (to 63.4%). A third party, the Congress of the People (COP), won over 22% of the vote but no seats.

The underlying problem in T&T stems from two common sources of poor FPTP performance: small assembly size and regionalism. The assembly size was stuck on 36 for many elections (at least as far back as 1966). That is very small for a country with now over 650,000 votes cast in the last two elections (and around a million eligible). By the Cube Root Rule, a country this size should have an assembly of 100-125 members. This problem was “addressed” in 2007 when the assembly was finally increased–all the way to 41.

The nature of regionalism can be seen by looking at the maps from recent elections at Psephos. As is common under FPTP, each party has strongholds and only a few seats change hands at any given election. The UNC dominates most of the center and southeast of Trinidad, whereas the PNM wins nearly every seat in Port of Spain and on Tobago. The partisan division mirrors the division between citizens of Indian or African descent, with the governing PNM relying on the latter group.

In this election, the UNC and COP have joined forces as the core components of a five-party pre-election coalition known as the People’s Partnership. It might seem that such a coalescence of the opposition would make a dramatic difference in the votes-seats conversion to the opposition’s advantage, but it may not. A quick and not-very-systematic perusal of the district-by-district results in 2007 shows only a few districts where the PNM won with less than 50% and where the combined UNC-COP vote would have meant PNM defeat. Most PNM districts were in fact won with majorities, whereas it was the UNC that often won with less than 50%. Still, if the race really is close, even a relative few seats could tip the result. A few seats could result in an over-representation of the Peoples Partnership even if it second in votes–and could even contribute to a spurious majority.

About the campaign, the Jamaica Observer (second link above) notes:

Music in the nation famed for calypso has played a key role in campaigning.

One PNM video shows red-clad crowds dancing at rallies in front of a smiling Manning, with slogans such as “free education” sliding across the screen to a catchy tune.

On the other side, a People’s Partnership campaign song contains the lyrics: “Allegations here, allegations there,” and shows pictures of flashy high-rise buildings alongside hospitals without beds.

“I can’t vote for that!” rings out the chorus.

Trinidad and Tobago would be better served by some form of proportional representation and has earned its place on the Watch List.

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* “Inherent and Contingent Factors in Reform Initiation in Plurality Systems,” in the edited volume by Andre Blais, To Keep or Change First Past the Post.

Expand the House

Peter Baker, writing in the New York Times, picks up a theme that has been prevalent here for a while: the US House needs to be expanded, specifically to improve the reapportionment process and to restore one-person-one-vote.*

Not counting a two-election increase when Alaska and Hawaii were added** the House size has not changed since the 1912 election. Back then the US had about 95 million people, or around a third what it has today!

The House used to be expanded periodically to track population size (see graph at the second-linked item). Why not now? As the NYT notes, the US judicial system is about to be asked that question.

Some advocates of increased House size have suggested a House of over 1,000 Representatives. That’s ridiculous–and hardly helpful to the cause. The cube-root law (again, see second link) would suggest 620-660. But, really, even 600, or 550, would help restore Representativeness considerably.

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Update: Nate Silver weighs in, but suggests focusing energies on expanding and reforming the Senate. I’m all for that, too.

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* To one of the arms of the federal government, anyway.


** That is, those states came into the union between censuses, and a seat was added for each. With the subsequent reapportionment, those states’ Representatives came at the expense of voters in other states, in order to return the House at 435.