The Squiggle Of Doom


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Polling estimates given to Sinn Féin by different polling companies since 2011 

Can nothing stop it?

Tom Louwerse, an Assistant Professor in Political Science at Trinity College Dublin, has taken issue with last weekend’s widely reported Millward Brown poll and how the media have interpreted it.

The hair-splitting boffin believes Sinn Féin’s popularity at 26% and that of Fine Gael at 22% – does not in fact definitively prove that Sinn Féin is the biggest party in the country.

Mr Louwerse, on The Irish Politics Forum, writes:

“First, the difference between Sinn Féin and Fine Gael falls within the margin of error of the poll. While the reported margin of error is 3.1%, this is the margin for any single party. If we calculate the margin of error for the difference between two parties, we find that it is 4.3%. That is just slightly bigger than the 4% gap. This means that even if there was no difference between the two parties among all likely voters, there is more than a 5% probability that a poll of 991 people* finds a difference between SF and FG of 4% or more. Just because of the people that randomly end up being surveyed. This is generally considered inadequate to base firm conclusions on.”

“Second, this calculation assumes the poll is a random sample from the population. In reality, it is very difficult to get a random sample, because (among other reasons) it is difficult to draw up a list of voters and to get them to participate in the polls. Therefore, the error margin might in fact be larger than the reported 3.1%. This is sometimes called ‘Pollster Induced Error’. The Irish Polling Indicator gives an (arguably rough) estimate of the Pollster Induced Error for Irish parties, which it estimates to be between 1.3 and 2.7 for Sinn Féin. That means that the error margin is likely to be at least 1.3 times the calculated margin. So, probably even the 4.3% margin of error is an optimistic estimate.”

“Third, polling estimates are prone to systematic error. This is visible in the fact that some polling companies have structurally higher estimates for Sinn Féin than others. In the graph below, we can see clearly that Millward Brown (green dots) generally has a higher estimate for Sinn Féin than other pollsters do. This effect can be calculated to be just under 1%. It is helpful to take these ‘house effects’ into account when interpreting polling results.”

“Therefore, one should be cautious to base sweeping statements on a single poll. The Irish Polling Indicator summarises information available from all Irish pollsters. This provides a more nuanced overview of the state of the parties. The Polling Indicator suggests that Fine Gael, Sinn Féin and Independents are on similar levels of support; based on the available data we cannot draw conclusions about who is the biggest of the three.

He adds:

“And bear in mind that 24% of those 991 gave a ‘Don’t know’ answer, so the effective sample size is in fact 753, which would yield an error margin of 4.9% for the difference between SF and FG. Mind the difference with the title of this blog post [below]: the title reflects the fact that we cannot say that SF is bigger based on the Millward Brown poll, but that does not mean that SF is certainly not bigger. It might be. We don’t know.

What?? Right.


Is Sinn Féin the biggest party according to new poll? No, no, no (Tom Louwerse, The Irish Politics Forum)

29 thoughts on “The Squiggle Of Doom

  1. Rob_G

    Another thing to bear in mind is that SF are toxic to transfers; while they do have an energised, growing base, the recent by-election showed that they still don’t attract many preferences.

    1. ScareySarahCarey

      I could well imagine the Cahill affair having the potential to hurt SF massively in terms of attracting transfers, especially in terms of picking up votes from left-leaning independents and the smaller leftish parties.

  2. Soundings

    So, the MBL poll had Sfers at 26% and FG at 22%, and there is a 3.1% margin of error, which means SF could be at 23% and FG at 25%?

    Or, SF at 29% and FG at 19%.

  3. cousinjack

    Based on 95% probability spread there is no significant change in SF support since April 2012.

    SF are marmite, No.1 or nothing

  4. Delacaravanio

    1. The trend line is going on one direction only: up

    2. The recent poll that put them ahead of FG was in the Sindo, a viscerally anti-Sinn Fein paper. A critical examination may indicate Sinn Fein are even more popular than the recent numbers suggest.

    3. The real thing driving their growth is not a rush of support in favour of Sinn Fein policies, rather it’s the rise of anti-politics and support for independents/non-conformists generally. This is why, despite (in some cases probably literally) having so many bodies in the closet they continue to draw support.

    1. andyourpointiswhatexactly

      I would have a massive prob-lame-o if SF got into power. I would genuinely think about emigrating, though I’m too old and too settled to, really. I despise them. Don’t get me wrong, I don’t have much time for the rest of ’em either but I have an *extreme* moral aversion to SF.
      Gawd, I’m getting into a temper even typing this.

        1. andyourpointiswhatexactly

          Yeah, silly me. Paying taxes, working and mortgage-free. I’m a total drain on “your” society.

        1. ScareySarahCarey

          The thing is that if there is continued talk of Sinn Fein in government you are probably likely going to see a big increase in anyone-but-Sinn-Fein transfers – where people will vote tactically on the basis of anyone but a Sinn Fein candidate
          e.g. people holding their noses and giving Fianna Fail a transfer on the basis of – well they might be crooks and robbers but they’re not as bad as Sinn Fein.

        2. delacaravanio

          I don’t think they attract racists. They are a republican and socialist party, so they’re pretty much anathema to right wingers generally.

          The closest we’ve come to racism in Ireland was McDowell’s populist citizenship referendum in 2004 which dropped jus soli citizenship from the constitution and redefined Irishness as an ethnic/familial concept. This was largely railroaded through on the back of a moral panic about refugees coming over here and having babies.

          Sinn Fein strongly opposed that amendment, as did the Labour party. The referendum was supported by Fianna Fail, the PDs and Fine Gael.

          1. Snix

            Funny that. The last nationalist and socialist party to have power in Europe were a beacon of racial tolerance. Think Germany 1933-45

      1. Rompsky

        I think I’d go too. Would be a big nudge closer anyway. Lets go together? Maybe somewhere with a beach?

      2. Snix


        Frightening and depressing thought of them getting anywhere near power.

        I would take a leaf out of Adam’s book (his refusal to pay water charges) and not pay ANY tax that I could withhold from any government containing SF.

  5. phil

    I have little interest in political parties, I admire some individuals in all of parties. I usually vote for the candidate that has little chance of beating an establishment individual , for encouragement like ….

    So whats the big deal/fear about Sin Fein ? Do people really think they will start murdering people if they get into power? Didnt most of our political parties start out by murdering people only to accept politics was the only way forward….

    I havent seen any strange behavour in the councils that SF control..

    I think if they did get into power, there wouldnt be much to fear , the large water protests show if enough people disagree with a policy while a government is in power , people can make a difference…

      1. Clampers Outside!

        I was pissing about on youtube and came across one of those ‘ancient aliens and the new world order’ videos which I often find entertaining (when you get one well made)… anyway, in among the NWO, Illuminati, the devil in the dollar and all that claptrap was a segment about the fluoridation of water and how it’s all about brainwashing the masses…. brilliant stuff it was :)

        1. Mick Flavin

          It’s no laughing matter Clampers. Don’t come crying to me when you’re being hauled away to the reeducation camp for not having your regulation “all-seeing eye” neck tattoo…

    1. cousinjack

      Perhaps a federal government covering these near europe atlantic islands is the answer, outside of the EU of course

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