Polls

Here I study the polls.

1. The most recent Buzzpeil poll was released on ().
2. The most recent Een Vandaag poll was released on ().
3. The most recent Politieke Barometer poll was released on ().
4. The most recent Peil.nl poll was released on ().
5. The most recent TNS-NIPO poll was released on ().

My average

Here is my weighted average of the polls. It reports a shift of seats relative to current parliament.

The effective number of parties is a measure for the fragmentation of a party system. The highest effective number ever reached in actual elections was 6.7 in 2010.

See the party profiles for a description of most parties.

• The OSF (Onafhankelijke Senaatsfractie; Independent Senate fraction) is an amalgam of regional parties that will not enter the national elections.
• The PP is the Pirate Party.

Coalitions

These tables are automatically generated — they may sometimes show weird coalitions. Still, Dutch politics are in such a state of advanced chaos that even weird coalitions may come to look appealing.

A five- or even a six-party coalition is not as remote as it might seem. Not all parties have to send ministers to the cabinet — they can support government from parliament, like Wilders supports Rutte’s VVD+CDA government. The left-wing equivalent would be a PvdA+D66+GL government.

Still, such a minority government would have to come to agreements with other parties that promise to support it. This combination of government parties and supporting parties would have to have a majority, and it is likely to be one of the coalitions mentioned here.

I add the likelihood of all coalitions that a party participates in to get at its likelihood to be in government. I do the same for all coalition types and sizes.

Raw data

There are three pollsters in Dutch politics: the Politieke Barometer, Peil.nl, and TNS-NIPO. Here’s the raw JSON data; below are some nice tables.

2011-2012 data are here.

Politieke Barometer

The Politieke Barometer publishes its poll every two weeks on a Thursday.

I trust the Politieke Barometer more than the other pollsters. It has a better score than the others for the right block and the traditional catch-all parties.

Politieke Barometer polls are usually quoted in the press, but don’t get anything near the exposure of Peil.nl polls.

Peil.nl

Peil.nl publishes its poll every week on Sunday.

Peil.nl is always out for sensational headlines. Protest parties SP and PVV usually poll better with Peil.nl than with the other two, and the same goes for the left block and for small parties.

Maurice de Hond, Peil.nl’s owner and a well-known political commentator in his own right, uses an open Internet poll to which anyone can subscribe. (I have.) This methodology is criticised time and again by the other two pollsters and political scientists, but if we compare his last polls to the election results he doesn’t do significantly worse than the other two. Part of the problem is that he has the best press contacts of the three, and his polls always draw headlines. Besides, if a TV programme needs a political pollster they always ask him. This won’t make him very popular among his colleagues.

TNS-NIPO

TNS-NIPO publishes its poll about every two months.

Generally TNS-NIPO is closer to the Politieke Barometer than to Peil.nl, with maybe a tad advantage for the centre parties.

TNS-NIPO polls rarely garner much attention in the press, except in De Volkskrant, which is a partner in this series of polls. That’s probably due to the confused release schedule, and TNS-NIPO’s annoying habit to release some polls only together with the next one.

Een Vandaag

Een Vandaag publishes its poll every month.

The poll is executed by Intomart GFK, which also polled in 2010 but not earlier, and did the worst job of the four pollsters. It seems even more left-minded than Peil.nl, which is no mean feat. Also, the single issue parties score better than in the other polls.

Buzzpeil

Buzzpeil polls through social media, without asking people what they vote. Or something. They create a new poll every week.

I’m not a big believer in this sort of poll, but they should get a chance to prove their assertions.

SEO

(SEO bait for Dutch-language searches)

Hier vindt u de peilingen over de Tweede Kamer-verkiezingen en de Nederlandse politiek van Peil.nl (Maurice de Hond), Synovate / Politieke Barometer en TNS-NIPO. Tevens bevat deze pagina mijn gemiddelde van de peilingen en een berekening van de mogelijke coalities.

Calculation methods

Finally a quick section on how I calculate my average and the coalitions.

Polls

I treat the polls as follows:

1. I established weighting factors for the pollsters based on past performance. They are
2. I also use a decay factor based on the poll’s age.
3. I assign bonus votes to some parties. See below.
4. I multiply the amount of seats of a party by both pollster weight and decay factor, and then add bonus votes. Then I add party scores from all polls and pollsters, and use the result as votes in an election according to the normal rules.
   In order to protect the small parties I use the system of highest remainders for rest seats, and I have no electoral threshold.

Poll bonus votes

I assign bonus votes to some parties. They are supposed to represent the number of voters that right now say they won’t vote (and thus aren’t counted in the polls) but eventually will vote after all.

The best example is the PVV: some people don’t dare to own up to the fact they’re going to vote for it, and that’s why the PVV handily beat the polls in both 2006 and 2010. I want to add that effect to my calculations.

Still, bonus votes are rather speculative, and I’ll try to validate the percentages. Expect frequent changes here.

Coalitions

The script creates all possible coalitions and then rejects the following ones:

1. Coalitions with PvdA, CDA, and VVD.
2. Coalitions with less than seats.
3. Coalitions of which a subset already has a majority of seats.
4. Coalitions with parties that have excluded each other. (See sidebar for the current exclusion list.)
5. Coalitions with two or more parties that have less than seats.
6. Coalitions whose smallest party has less than seats, unless that party gives the coalition its majority.

The table shows the remaining coalitions.

Coalition likelihood

The likelihood of a coalition is calculated by the following formula that I tweaked by hand (there are few theoretical underpinnings here). I don’t doubt I’ll make frequent changes.

The formula is
1/SIZE * MAJORITY * SMALLEST * RELATION * SENATE

SIZE

the number of parties in the coalition

MAJORITY

the majority of the coalition (seats over 75)

SMALLEST

the size of the smallest party

RELATION

Each pair of parties has a relation from 0 (excluded) to 3 (preferred). The sidebar shows which parties have which relations.
The variable is the sum of the worst relations in the coalition.
(Coalitions in which any two parties have relation 0 are rejected automatically, so that value doesn’t occur.)

SENATE

Is 1 if the coalition has a majority in the senate, 0.5 if it does not.

Once the likelihood of all coalitions has been calculated, the results are treated as votes in an election for 100 seats. This yields the percentages that are shown in the table.

Pollster quality

Here I compare the final polls of the pollsters to the election outcome. I hope this makes clear why I consider the Politieke Barometer the best pollster.

The average error averages all errors of each pollster, where the most recent error counts double.

Lower numbers are better. The calculation is as follows:

1. For each misassigned seat one point is given. In 2003 the Barometer gave the CDA two seats too few, the LPF one too few, the CU two too many, and the PvdA one too many. Thus it misassigned three seats and gets three points.
2. If the pollster sees a party entering parliament but it wins zero seats, or if a party enters parliament but a pollster gives it zero seats, it gets an extra point.
   In 2010 Een Vandaag and TNS-NIPO both gave TON one seat, while it did not enter parliament. They both get a point because they were wrong about TON, in addition to the point for the misassigned seat.
3. If the pollster incorrectly predicts the largest party it gets an extra point. In 2003 all pollsters showed the PvdA larger than the CDA, and they were all wrong and all get an extra point.

The PAM is the Politieke Aandelenmarkt (Political Stock Market), an initiative of De Volkskrant, which was supposed to give better results than the pollsters but didn’t. I played in 2006.

In 2010 I drew an average of the polls; I think I just averaged the numbers without weighting or other subtle tweaks. Since the pollsters were fairly close I also was fairly close. In 2012 I use the results of my poll average.

Poll data over 2002-2006 come from Cijfers.net.

2012

PvdA and especially VVD were underestimated by all pollsters — clearly a last-minute prime-minister race effect boosted them both, mostly to the detriment of the SP. Also, the PVV was overestimated for the first time, and by a lot less seats than it was underestimated in 2010. The theory that they lost last-minute seats to the VVD is defensible. So maybe the PVV is becoming predictable.

2010

In 2010 all pollsters underestimated Wilders’s PVV for the second time running, which is why it is a difficult party to predict. Some polls again missed the fact that the PVV would be the only extreme right party in parliament.

Also, the CU’s loss of one seat was not predicted (and Intomart even predicted a ridiculous 10 seats).

2006

All pollsters underestimated Wilders’s PVV, and only TNS-NIPO saw that it would be the only extreme right party — the others have one or two others win a few seats. Also, the SP polls diverged very widely.

2003

All pollsters but the PAM had the PvdA a tiny bit larger than the CDA, but in the elections the CDA became the biggest. This is a classic prime-minister-race effect.

2002

The big surprise was that the CDA grew a lot more than expected, and GL and CU lost one seat instead of winning a few. CU to CDA is a logical movement.

All pollsters got big newcomer LPF (List Pim Fortuyn) about right.

1998

Data as yet incomplete; Peil.nl is missing. And to be honest I’m not totally sure I got the very badly formatted data right, or whether it’s reliable. I mean, did they really predict 3 seats for Janmaat?