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.
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.

6 thoughts on “Jamaica 2011: As good as PR–or not (updated)

  1. “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?”

    At least among the Nationalist (pro-United Ireland) parties in Northern Ireland, the SDLP is generally considered further to the right than Sinn Fein (which is a nationalist slogan in Irish), so that might count, although in the broader spectrum of UK politics both are economically leftist (indeed, like pretty much every party in NI, except possibly the UUP).


  2. I remember it being pointed out, possibly by MSS, that the results of elections to the American House of Representatives tend to be quite proportional, if a party takes about 53% of the vote they tend to wind up with about 54% of the seats.

    It may be the existence of third parties who nevertheless get significant national support that cause the skew between seats and votes in single member plurality systems. The share of seats that the third parties fail to obtain tend to accrue to the largest party.


  3. Ed, at the US House level, it is true that results tend to be quite proportional. At state level, there are some pretty egregious cases of disproportionality.

    Obviously, Jamaica and the US share having fairly “pure” two-party systems, yet until recently, Jamaica had far more disproportional results than the US House typically shows.

    In the larger data set (201 elections in FPTP-parliamentary jurisdictions), the size of the vote for the third party actually explains less of the variation in the largest party’s advantage ratio than does the difference in votes between the top two parties (see fn#2, above). I did not expect that, but there you go.


  4. In other true Caribbean nations (Saint Lucia and Dominica), the more right-wing of the major parties are called “United Workers Party” (sounds like the parties that are created after a communist take-over, when all left-wing parties are force to merge with the Communists…).

    For other side, it is common the european conservative partes having names like “popular”, “volks”, “populaire”, etc.


  5. This article is wrong though.

    In the 2011 election the PNP won 53.3% of the vote and the JLP won 46.6%.

    Also in a recount the PNP got 42 seats and the JLP got 21 seats.

    So the PNP got 66.7% of the seats for a Seat Advantage Ratio of 1.25.

    It was asked how many other countries have a more right-wing party called “Labour”, but in the Caribbean it is not unusual as most of the voters since universal suffrage have been working class and any party which didn’t at least appear to be for the working class doesn’t stand a chance of being elected to form a government on its own. Ever. Had the JLP been called the National Conservative Party or Conservative Party of Jamaica or something like that it would have never gotten a seat from the start as those who would gravitate to a party openly described as “conservative” (the business class) would be too dispersed to give them a win in any one constituency. So it chose the name “Labour” (in addition it was founded off a trade union (another reason for the name “Labour”) and became allied to big business)

    So you have the Jamaica Labour Party and People’s National Party in Jamaica; the Democratic Labour Party (which was once aligned with the JLP in a larger federal Democratic Labour Party during the time of the West Indian federation) and Barbados Labour Party (which had been aligned with the PNP during the federation) in Barbados; the defunct Democratic Labour Party in Trinidad and the People’s National Movement; the United Workers Party and St. Lucia Labour Party in St. Lucia; the defunct St. Vincent Labour Party (now a part of the Unity Labour Party) facing off against the People’s Political Party (also defunct) in St. Vincent….


  6. Obviously, what was written above was based on preliminary results (as reported in the linked press item). But I don’t think I have ever seen such a large change from preliminary to final results as this. That’s an 8-percent reduction in the reported votes, although it is noteworthy that only one seat swung.

    This makes it even more interesting. Where did those additional JLP votes come from? Apparently from seats already safely won.

    When I get a chance, I will update what I wrote about the election in comparative perspective. Thank you, Jon, for calling attention to the revised figures.


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