The numbers on this page are not (quite) scientific. If you’re looking for officially quotable, pol-sci-validated numbers, go to the Peilingwijzer instead.
That said, my tables also include earlier poll results and coalition predictions. Also, I personally believe the interface is nicer. Finally, it’s in English, and not in Dutch.
Pollster comparison. Who’s best?
Here I study the Dutch polls.
My weighted average of the polls is designed to flatten out trends, so that outliers are somewhat ignored, and only persistent trends accepted. It reports a shift of seats relative to current parliament.
It reports new parties only if they have at least one seat in the last poll of every pollster. This simple rule of thumb helps reduce tiny-party clutter wonderfully.
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 8.1 in 2017.
Here’s an overview of the latest poll by each pollster. The table also indicates if a party or block/type gained or lost more than 1 seat in the latest poll.
The Bullish and Bearish columns show:
The Weight value gives the relative weight of the poll in the calculation of the Now column above. However, the Now column also uses older polls that fall before the second column’s date, so the average isn’t dependent on these last polls alone.
See the party profiles for a description of most parties. Below are the ones I never wrote a party profile for.
The OSF (Onafhankelijke Senaatsfractie; Independent Senate fraction) is an amalgam of regional parties that will not enter the national elections.
The PP is the Dutch Pirate Party. In 2012 hovered on the brink of becoming a serious party. Nowadays it’s led by a former model, and had some trouble which seem to have cost it its entry into parliament.
For an introduction to Dutch coalitions I advise you to read this article series that I wrote for the 2010 elections. The details are slightly different today, but the broad overview is still valid.
The coalition tables are automatically generated and 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 supported Rutte I (VVD+CDA). The left-wing equivalent would be a PvdA+D66+GL government.
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 is likely to be one of the coalitions mentioned here.
Also, while CDA and VVD are officially excluding Wilders, I’m going to assume they may change their minds. Therefore, PVV+CDA and PVV+VVD coalitions are now shown in the table, though at 50% of their usual likelihood.
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.
How do I calculate my average and the coalitions. (Warning: I have zero knowledge of statistics.)
I treat the polls as follows:
The most negative opinion prevails. So if the SP indicates it can work with the VVD, but the VVD says it can’t work with the SP, their relation is Excluded.
The script creates all possible coalitions and then rejects the following ones:
The table shows the remaining coalitions.
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 * PVV
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.
There are four pollsters in Dutch politics: the Politieke Barometer, Peil.nl, Een Vandaag, and TNS-NIPO. Here’s the raw JSON data; below are some nice tables.
2016-election 2017 data are here.
2011-2015 data are here.
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 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 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 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 then-four pollsters. It seems to bend slightly leftward.
I&O Research is a new pollster. I don’t yet know how well it performs, or even how often it will publish polls. From what I’ve seen so far their polls tend to over-estimate the left and be all over the place.