It's been a night of frustration for Blair McDougall, the No camp's embarrassment of a campaign chief. He must have hoped that the new YouGov poll would replicate the post-debate increase in the No lead reported by Survation a couple of days ago, but instead it has shown no change whatsoever since the last poll from the firm several weeks ago. Bear in mind that YouGov have in recent times overtaken Ipsos-Mori to become the outright most No-friendly pollster, largely due to the notorious "Kellner Correction" which artificially lowers the Yes vote, so the following figures should be seen in that light.
Should Scotland be an independent country?
Yes 39% (n/c)
No 61% (n/c)
On the figures that take account of Don't Knows there has been a 1% increase in the No vote, which is of no statistical significance at all -
Yes 35% (n/c)
No 55% (+1)
Now, to be fair, there are two ways in which the No campaign could argue that this poll is theoretically consistent with a substantial post-debate bounce for No, even if that's not showing up on the headline figures - but both are problematical for them. The first way is to point out that, unlike the Survation poll, only half of the fieldwork actually took place after the debate, so it's possible that the post-debate part of the sample was much better for No. The problem is that this would imply there must have been a swing to Yes in the pre-debate part of the sample, otherwise the overall Yes vote would be lower. That's surely not something that McDougall Central would be comfortable with, because we know that debate bounces can recede very quickly.
The second way is to point out that the last two YouGov polls were probably understating the Yes vote, because they both showed swings to No at a time when other pollsters were detecting no such thing. So it could be suggested that the Yes vote has actually fallen from 41-42% (with Don't Knows excluded), which is the high watermark YouGov showed in the spring. But that would also be a problematical claim, because the No campaign were all too eager to insist that the changes shown in the last two polls were real, and they'd have to implicitly accept they were leading us up the garden path.
It's important to stress that YouGov are one of only two BPC pollsters (the other is TNS) who don't filter or weight their headline numbers by likelihood to vote. However, like TNS, they do make additional turnout-adjusted figures available. As far as I know, those figures haven't been released yet for this poll, so that'll be the first thing to look out for when the datasets appear, presumably tomorrow. It's impossible to say whether the filtered results will be any different - they weren't in the last YouGov poll, but in the last-but-one poll the No lead was a full 4% lower among respondents who say they will definitely vote.
It's been well-rehearsed that YouGov have acted in a thoroughly reprehensible manner since this long referendum campaign began. When I or others raise question marks about the methodologies of various pollsters, it's sometimes asked : "Are you seriously saying that the pollsters are consciously biased?" And generally the answer to that question is "no", but YouGov is a partial exception. I'd say they now occupy a no-man's-land somewhere between neutrality and outright pro-No bias. Both Peter Kellner and Laurence Janta-Lipinski have published commentary on the referendum that has utilised familiar No campaign attack lines, and it's very hard to trust a firm capable of doing that to be scrupulously neutral in devising its methodology.
Nevertheless, just for once I can give a very small piece of credit to YouGov, because in this poll they have made two very sensible methodological changes, albeit arguably of the "too little, too late" variety. They've followed in Panelbase's footsteps by introducing weighting by country of birth, which will have the effect of slightly reducing the No lead. In this case it has only reduced what would otherwise have been a 62/38 split to 61/39, but once the hoo-ha over the debate fades away or goes into reverse, we may soon be back into a situation where a 2% or 4% decrease in the No lead will look a hell of a lot more significant. Incidentally, if it's gradually becoming the new orthodoxy that weighting by country of birth is a wise idea, then it's highly likely that the No lead in the Survation poll should have been a bit lower.
YouGov's other change is to start interviewing 16 and 17 year olds, which is a ridiculously long-overdue step, because other pollsters have been doing it throughout the campaign. It's very hard to understand how Kellner can try to pull rank on other pollsters when his own firm has been guilty of such an amateurish omission for so long.
Welcome though these changes are, neither of them can even begin to make up for the fact that the "Kellner Correction" remains in place, and the obsessive secrecy over the effect it is having continues. Anthony Wells has a semi-detached relationship with YouGov that I don't fully understand, but his inside knowledge was sufficient to let us know instantly what the figures in this poll would have been if the new methodological changes hadn't been made. And yet still no-one will tell us what the numbers would be if the "Kellner Correction" was removed. When I asked Janta-Lipinski a few weeks ago, he initially tried to change the subject, before boasting about the firm's secretiveness and the fact that we weren't entitled to that kind of information.
More details on this poll, and a Poll of Polls update, can be found HERE.