Yes campaign are just 2% from victory in remarkable YouGov poll

It was probably always inevitable that there would be some reversion to the mean from YouGov after the firm showed an almost unbelievable 12% swing over the space of a month, but the Yes campaign will take enormous heart from this, their second-highest ever showing from a once firmly No-friendly pollster - higher even than in the YouGov poll just over a week ago that set this campaign alight.

Should Scotland be an independent country?

Yes 48% (-3)

No 52% (+3)

From the moment that Survation published their poll yesterday showing only a very tiny swing to Yes, it always seemed likely that there hadn't been any kind of bandwagon effect for the Yes campaign since the weekend - hardly surprising given the mind-boggling onslaught they've had to endure over the last few days from the entire London establishment, and especially the London media.  But the big remaining question was - had Yes gone backwards, or had they retained their big gains?  There is now strong evidence pointing to the latter, and it is coming from two different pollsters.  Survation showed Yes holding firm at an all-time high of 47%, while the variation between the last three YouGov polls (of between 47% and 51% for Yes) is also entirely consistent with a relatively steady position, masked by the absolutely normal 'noise' that is caused by the 3% margin of error.  It therefore seems that the voters who have recently been won over to the Yes side are sticking with the Yes side, in spite of the onslaught.  The best evidence of that is YouGov's fieldwork dates - this poll didn't even finish until earlier today, and started only on Tuesday.

I've no idea what the private polling and collated canvassing results on both sides are showing, but certainly from the perspective of anyone who just follows this campaign from the published polls, there would have been good reason to wonder if the No campaign were going to achieve a big swing in this poll.  Throughout this year, Survation have consistently reported a much higher Yes vote than YouGov, and in some ways it scarcely seemed credible that Survation could show Yes holding steady at 47% without that being followed by Yes slipping below 47% in the subsequent YouGov poll.  OK, we've seen convergence, but surely even after convergence you'd expect to see the normal pecking order of Yes-friendly and No-friendly firms remain in place to a more limited degree?  It appears not.  Two rogue polls in a row from YouGov was just about imaginable, but a third is not - so we can now say it's official.  YouGov are no longer a No-friendly pollster, and whether that's in spite of or because of the "Kellner Correction" is something we can only speculate on for now.  Indeed, both TNS and YouGov are as of this moment more Yes-friendly than Survation, so it seems that all the old certainties have gone as we contemplate the crucial final few days.

Obviously Yes campaigners will react to the closeness of the polls by stepping up (even further) their efforts to win over undecideds and soft No voters - and that is absolutely the right thing to do, because we don't know exactly how many more people we need.  But as of tonight (and I may well revise this opinion when we get the ICM poll tomorrow) we have at last reached the position where it is just about possible that even if the pollsters have their methodology absolutely right, Yes could be in the lead already.  Across all firms, the last five polls have reported Yes votes of 48%, 47%, 51%, 48% and 50%.  Bearing in mind the margin of error, that means there is a genuine chance that Yes are ahead, although the balance of odds remain substantially in favour of No retaining a very slender advantage.

But things become more interesting still when you take into account the concerns that pollsters themselves (such as Martin Boon) have openly expressed about the limited confidence they can have in the accuracy of their methodology, due to the unusual nature of the contest.  If we therefore assume that the real world margin of error is significantly higher than 3%, then the chances that Yes are already in the lead immediately look much more substantial.

In the Poll of Polls below, you'll see that the Yes vote has slipped back slightly - that's simply because I only use one poll per firm, and therefore this new YouGov poll has replaced the one that had Yes in a slight lead.  But John Curtice's Poll of Polls has Yes remaining at the heady heights of 48%, and that's partly because his methodology takes into account all of the last three YouGov polls.  In the past, I would have said that approach is a weakness, because in a campaign which has been distinguished by different firms diverging from each other markedly, you really have to ensure that the weight given to each firm remains constant over time.  However, now that some of the pollsters have converged, the one big strength of the Curtice approach may be making itself felt - ie. that it uses only the most recent polls, and the results therefore aren't artificially 'held back' by the inclusion of polls from several weeks ago.  If it can be assumed that there is no remaining bias for Yes or No in the methodology of any pollster, but that there was until very recently, then for the first time the Curtice Poll of Polls may be the best guide to the state of play and to the trends.  It remains to be seen if that's the case, though, because it's still an open question whether ICM and Ipsos-Mori (and indeed Opinium, who are apparently about to publish their first referendum poll) will join the general pattern of convergence.

I haven't been closely following the mainstream media reporting of the Survation poll, so I was shocked (although I shouldn't have been) to see a comment suggesting that many journalists made a bogus apples-and-oranges comparison between that poll and the weekend YouGov poll, in order to wrongly claim that the Yes vote had slipped.  If that's true, we really must demand consistency - tonight's poll should therefore be compared to yesterday's Survation poll, and not to the previous YouGov poll.  That means that Yes should be reported as being 1% up, and No should be reported as being 1% down.

They really can't have it both ways, no matter how much they'd like to.

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REQUIRED SWINGS

Swing required for 1 out of 6 pollsters to show Yes ahead or level : 0.5%

Swing required for 2 out of 6 pollsters to show Yes ahead or level : 2.0%

Swing required for 3 out of 6 pollsters to show Yes ahead or level : 2.5%

Swing required for 4 out of 6 pollsters to show Yes ahead or level : 3.0%

Swing required for 5 out of 6 pollsters to show Yes ahead or level : 4.5%

Swing required for 6 out of 6 pollsters to show Yes ahead or level : 7.0%

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SCOT GOES POP POLL OF POLLS

MEAN AVERAGE (excluding Don't Knows) :

Yes 46.3% (-0.7)
No 53.7% (+0.7)

MEAN AVERAGE (not excluding Don't Knows) :

Yes 41.2% (-0.3)
No 47.7% (+0.9)

MEDIAN AVERAGE (excluding Don't Knows) :

Yes 47.0% (-0.2)
No 53.0% (+0.2)

(The Poll of Polls is based on a rolling average of the most recent poll from each of the pollsters that have been active in the referendum campaign since September 2013, and that adhere to British Polling Council rules. At present, there are six - YouGov, TNS-BMRB, Survation, Panelbase, Ipsos-Mori and ICM. Whenever a new poll is published, it replaces the last poll from the same company in the sample. Changes in the Poll of Polls are generally glacial in nature due to the fact that only a small portion of the sample is updated each time.)

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When I heard that George Galloway was taking part in the TV debate at the Hydro, I naturally assumed that the BBC had gone over Better Together's heads to invite him.  When it was announced at the start of the programme that Better Together had actually nominated him and he was specifically there on their behalf, my jaw dropped to the floor.  OK, it must have been some kind of tactical gambit to appeal to traditional Labour voters, but what kind of message do they think it sends out to put forward the leader of the Scottish Tories, and a far-left politician who was expelled from Labour years ago?  Oh well, at least they've got the anti-German vote sewn up now.