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:
|Ipsos / Eén Vandaag||
|NIPO / Kantar||
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: Ipsos / Eén Vandaag, Peil.nl, NIPO / Kantar, and I&O Researxh. Here’s the raw JSON data; below are some nice tables.
2016-election 2017 data are here.
2011-2015 data are here.
I started collecting these data in June 2011. I do not know of any comprehensive source for poll data before June 2011.
Ipsos used to publish its poll every two weeks on a Thursday, but switched to the last Tuesday of the month since becoming the pollster of choice of political TV programme Eén Vandaag. This poll is also called the Politieke Barometer, but that brand seems to have been discontinued.
I trust Ipsos more than the other pollsters. It has a better score than the others for the right block and the traditional catch-all parties.
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.
NIPO / Kantar publishes its poll about every two months. See also the poll page, which is updated more frequently than the press release page.
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.