Wednesday, June 22, 2016

Leave take slender lead in final Opinium poll

I'm sure we'll have more polls tonight (Referendum Eve is very much like Christmas Eve, as veterans of the indyref will recall), but we've already had two so far today - and the news is mixed.  Leave will be delighted to take a 1% lead with Opinium, who in recent weeks have become one of the most Remain-friendly online firms after introducing methodological changes that essentially made their weighted sample more like a typical telephone sample.  But Survey Monkey show a small swing in the opposite direction, which leaves open the obvious possibility that nothing much has changed, and that any apparent shifts in either poll are just caused by normal sampling variation.  Both polls show a statistical tie - ie. even if the methodology is bang on accurate, it's not possible to say which side is in the lead due to the standard margin of error.  (I gather Opinium may have used a larger sample than usual, but even enormous samples have a margin of error.)

Should the United Kingdom remain a member of the European Union or leave the European Union?

Opinium :

Remain 44% (n/c)
Leave 45% (+1)

Survey Monkey :

Remain: 50% (+2)
Leave: 47% (-2)


I've just received the Survey Monkey press release by email, in which they describe the small reported shift to Remain as "decisive".  I must say that's a bizarre summary, and not just because Opinium have directly contradicted their findings.  Even with a sample size of 4000, it's absurdly bold to suggest that a 2% swing in a stand-alone poll is necessarily significant, or indeed that a 3% gap means that you've definitely got the correct side in the lead.  I suspect that Survey Monkey, just like BMG a few days ago, may be overstating their sense of certainty in the hope of gaining bragging rights for years to come if they just happen to be right.

17 comments:

  1. You're always quick with the latest polling news. Well done James on a fine EU blog this year.

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  2. Seconded. This blog is my go to destination for the last polling news.

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  3. Actually, the fact that you analyze them so well in real time is amazing. I am confused. Isn't it survey monkey that provided a huge shift to leave just two days ago? And isn't 4000 a huge sample for the population?

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    1. No, they showed a very small shift to Leave yesterday (just 1%). I can't find a margin of error on the press release, but with a country the size of the UK it must be at least 1.5%.

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    2. Yeah. 1.5 is pretty small. Thanks!

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    3. Yeah. 1.5 is pretty small. Thanks!

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  4. Absolutely. Bang up to date. Much appreciated.

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  5. James, is the survey monkey poll showing 3% don't know?

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  6. Just had a look at the datasets. Scotland sample pro-remain.

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    1. Any actual figures for Scotland, Marcia?

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    2. Opinium - Remain 52 Leave 35 DK 11 2 Won't say.

      When pressed the DK's are leaning 37% Remain 22% with rest still undecided.

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  7. Glasgow Working Class 2June 22, 2016 at 6:15 PM

    Knickerless scumbag threatening to crawl to the EU if we vote leave. How will we transport our exports silly moo.

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  8. TNS poll Mike Smithson, 2% lead for leave, game on!

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  9. Actually, the fact that you analyze them so well in real time is amazing. I am confused. Isn't it survey monkey that provided a huge shift to leave just two days ago? And isn't 4000 a huge sample for the population?

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  10. GWC2 You are a deviant weirdo.

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