TNS-BMRB poll suggests Yes campaign have retained their big gains among definite voters

This month's edition of the TNS-BMRB referendum poll has just been released, and it shows an almost identical position to last month.  Among respondents who are certain to vote, the Yes campaign have retained three-quarters of the significant gains they made in the previous poll, when the gap was slashed from 13% to 9%.

Should Scotland be an independent country? (Definite voters only)

Yes 34% (-1)
No 44% (n/c)

A 1% slippage in the Yes vote is of course statistically insignificant.  Although TNS don't use the figures for definite voters as their headline numbers, other pollsters would do (notably Ipsos-Mori), so it's striking that on this crucial measure the Yes campaign have once again hit the kind of heady heights with a face-to-face pollster that they've previously only been accustomed to reaching with online firms.  We'll have to wait and see what the exact figures are after Don't Knows are stripped out, but a rough calculation suggests that they'll be somewhere in the region of Yes 44%, No 56%, which would be very much in line with the picture painted in recent times by the relatively Yes-friendly online pollster Survation.  [UPDATE : The datasets confirm it is indeed Yes 44%, No 56% after rounding.  Apologies for the incorrect update earlier.]

The headline numbers which take the whole sample into account show that Yes have managed to stay on 30% - their high watermark of the campaign so far (or at least the record high since TNS introduced a radical methodological change which hugely increased the reported number of undecided respondents).  The No lead remains stuck at 12% - which is similarly the record low for the campaign so far.

Should Scotland be an independent country?

Yes 30% (n/c)
No 42% (n/c)

The rough calculation on those numbers suggest that with Don't Knows excluded it's most likely to be Yes 42%, No 58%.  However, I said exactly the same thing last month, and it turned out that the Yes vote had fallen victim to the rounding, and was actually still at 41%.  It would certainly be a big psychological boost if it turned out to be 42% this time, because it would be the highest Yes vote that TNS have reported in the campaign so far on that particular measure.  [UPDATE : Unfortunately, John Curtice has revealed that it's once again Yes 41%, No 59% on the rounded numbers.]

As is always the case with TNS-BMRB, the fieldwork for this poll is ridiculously out of date.  It took place between the 21st and the 28th of May, which presumably means that well over half of the interviews were conducted before anyone had even heard the results of the European elections.  So if there was any swing to Yes directly generated by revulsion towards UKIP's victory south of the border, we wouldn't necessarily expect it to show up in this poll.  However, the good news is that the fieldwork did take place well after last month's ICM poll, and the fact that it has failed to show any increase in the No lead at all is another powerful indication that the ICM poll was probably reporting a misleading trend. Indeed, if we look at this poll in combination with the most recent Panelbase and Survation polls (and to some extent last week's Ipsos-Mori poll, although that's harder to interpret because it was the first for three months), I'd say we now have reasonably conclusive proof that the increase in the No lead reported by ICM was an illusion.  However, it's still open to question whether it was caused by a particularly extreme example of margin of error "noise", or by the absurd methodological change which may have unsettled respondents before they were asked the main referendum question, or indeed by a combination of both factors.

TNS have done in this poll what ICM and Ipsos-Mori do as a matter of routine, and pressed undecided voters on how they are most likely to vote.  The results are highly encouraging for the Yes camp -

Yes 19%
No 15%

The remaining two-thirds of Don't Knows were still unable to say which way they were inclined to jump.  But it's important to remember that TNS always report a far higher number of undecided voters than any other pollster - Don't Knows make up 28% of the entire sample in this particular poll.  So a 4% lead for Yes among this group is certainly a matter of some significance.  Presumably we'll shortly find out what the figures for the whole sample are when 'undecided leaners' are added in, but my rough calculation (this is becoming a habit!) suggests that the position will probably be something like Yes 35%, No 46% - or Yes 43%, No 57% after the hard-core of undecideds are excluded.

I couldn't help but raise a smile at the revelation on the front page of the Herald that the No campaign are dismissing the lead for Yes among undecided respondents, with "a small sample size" being the stock excuse for the evening.  It's only ONE WEEK since Blair McDougall was crowing about the fact that Don't Knows in the Ipsos-Mori poll were breaking slightly more for No - even though that was based on a smaller sample.  They really have absolutely no shame.

[UPDATE : I'm slightly confused after reading John Curtice's blog, because he suggests that undecided voters are breaking exactly evenly in this poll.  I can only assume therefore that the 19%-15% split is among definite voters only.  Still no word on what the numbers for the whole sample are once 'undecided leaners' are added in, although presumably among definite voters the Yes vote will be lifted up to either 44% or 45%.]

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SCOT GOES POP POLL OF POLLS

No change in the TNS headline numbers naturally means no change in the Poll of Polls, so this update is mostly a very simple cut-and-paste job!

MEAN AVERAGE (excluding Don't Knows) :

Yes 42.8% (n/c)
No 57.2% (n/c)

MEAN AVERAGE (not excluding Don't Knows) :

Yes 35.7% (n/c)
No 47.8% (n/c)

MEDIAN AVERAGE (excluding Don't Knows) :

Yes 42.3% (n/c)
No 57.7% (n/c)

(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.)

Here are the long-term trend figures, with the updates prior to Easter recalculated to exclude the inactive pollster Angus Reid...

The No campaign's lead in the Poll of Polls mean average (not excluding Don't Knows) :

Sep 2013 - 21.6%
Sep 2013 - 21.4%
Sep 2013 - 19.4%
Oct 2013 - 18.8%
Oct 2013 - 18.4%
Oct 2013 - 18.2%
Nov 2013 - 18.4%
Nov 2013 - 18.0%
Dec 2013 - 17.0%
Dec 2013 - 16.8%
Dec 2013 - 16.4%
Jan 2014 - 14.4%
Jan 2014 - 14.2%
Jan 2014 - 14.2%
Jan 2014 - 15.2%
Feb 2014 - 15.0%
Feb 2014 - 15.5%
Feb 2014 - 15.5%
Feb 2014 - 13.7%
Feb 2014 - 13.3%
Feb 2014 - 14.2%
Mar 2014 - 14.2%
Mar 2014 - 14.5%
Mar 2014 - 14.5%
Mar 2014 - 14.7%
Mar 2014 - 13.8%
Mar 2014 - 13.0%
Mar 2014 - 12.5%
Apr 2014 - 12.5%
Apr 2014 - 12.7%
Apr 2014 - 12.7%
Apr 2014 - 12.3%
Apr 2014 - 11.4%
May 2014 - 11.2%
May 2014 - 11.2%
May 2014 - 11.5%
May 2014 - 13.3%
Jun 2014 - 12.1%
Jun 2014 - 12.1%