Yes campaign open up eight-point lead in stunning poll from "gold standard" ICM

Just one day after their extraordinary telephone poll that put Yes within 1% of victory, the UK's "gold standard" polling organisation ICM have gone one better by producing an online poll showing Yes in an outright lead - and a lead of eight points, no less.  The percentage changes listed below are measured from the last ICM online poll, because that's the one it's directly comparable to,

Should Scotland be an independent country?

Yes 54% (+9)
No 46% (-9)

There's also a new Opinium poll out tonight - no percentage change figures are possible for this one, because it's the first referendum poll Opinium have produced.

Yes 47.4%
No 52.6%

Since I began this post, a Panelbase poll has also been published, so I'm going to analyse all of today's four polls in a fresh post.  Before I do that, though, I just want to deal with a point about the ICM poll that has already been discussed at length in the comment section below and elsewhere.  It is categorically not the case that it should be regarded as a lesser poll because it had a slightly lower sample size than usual (705 as opposed to the more typical 1000).  According to the very handy MOE calculator on the ComRes website, the margin of error for a poll of 700 respondents is approximately 3.7% - which is only fractionally higher than the 3% margin of error for a poll of 1000.  Someone suggested below that I have said in the past that, by definition, polls of this size cannot be regarded as statistically reliable.  I've never said that, because it isn't true.  The only thing I can think of is that I put a health warning on YouGov "polls" of roughly this size in the run-up to the European elections, but that's because they weren't proper polls - they were aggregates of subsamples from GB-wide polls.  The key factor in determining whether a poll is legitimate is not the sample size (unless it is absurdly small) but rather whether it was properly weighted.  As far as I know, this one was weighted in exactly the same way as any other ICM online poll would be - I'm quite sure Professor Curtice would have been the first to flag it up if that had not been the case.  So it should be regarded as a legitimate ICM online poll in exactly the same way as any other ICM online poll.

Indeed, we've had smaller polls than this during the campaign - two of the three Angus Reid polls that were published last year had samples of 500 or so, and although that fact was noted in passing, it wasn't perceived as significantly detracting from the credibility of the results.  In the US, samples of 500 would be regarded as fairly routine, and it would certainly be seen as very odd to use that as an excuse for ignoring any given poll.  And what about the ICM poll with a sample of 500 which the media seized upon as 'absolute proof' that Alistair Darling had defeated Alex Salmond in the first debate?  I don't recall Euan McColm casting doubts on the reliability of that one.  (I did, as it happens, as did Professor Curtice to some extent, but that was mostly because of the extreme upweighting that had gone on.)

It's therefore extremely troubling that the title Curtice uses for his blogpost on the ICM poll is "ICM Put Yes Ahead - Perhaps".  Does the "perhaps" refer to the 3.7% margin of error?  If so, shouldn't any verdict on any standard poll of 1000 people also automatically have the word "perhaps" attached to the title, because all of those polls have margins of error of 3%?  Or is there some kind of mystical gulf between the numbers 3 and 3.7 that I've failed to comprehend so far?  It just seems like a ludicrous double-standard.  I note that a report on the BBC website is mentioning all of the other polls today, but not the ICM one - I can't help wondering if that's been caused by a misinterpretation of Curtice's title as meaning that this is somehow not a "proper poll".  By the way, I have no complaint about Curtice's decision to add this poll to his Poll of Polls, but to give it a slightly lower weighting in proportion with the sample size - that seems perfectly reasonable to me.  But it should also be seen absolutely, unambiguously as an endorsement of the poll's legitimacy, because that's exactly what it is.

You probably don't need me to point out that you would have to go to the extreme end of a 3.7% margin of error to take this poll to a result that does not have Yes clearly in the lead.  Given the strength of the evidence from other pollsters that No are either slightly ahead or level, perhaps we do need to assume that ICM have produced a result that is at the extreme end of the margin of error, but so what?  We could be forgiven for making exactly the same assumption about today's Survation poll, which is showing a lower Yes vote than others.

Further analysis of all of today's four polls, plus a Poll of Polls update, will appear HERE.