There's just one thing I don't understand, Professor

See if you can reconcile two statements from Professor John Curtice, made within the same blogpost about the new female-only Survation poll. I must say I'm struggling.

Statement 1 : "In the company’s last regular monthly omnibus for the Daily Record in July, Yes support amongst women stood at 40%, exactly the same as today’s poll. Meanwhile the equivalent figures for the three months before that were June, 41%, May 38%, and April just 36%."

What he's pointing out here is that support for Yes among women in this poll is roughly the same as it was in two previous Survation polls which had Yes at 47% among the entire sample, and is significantly higher than in two earlier polls that had Yes at 44-45%. In other words, although it's impossible to draw firm conclusions, the new poll is perfectly consistent with Yes being above 45% across the population as a whole.

Statement 2 : "Of course what the poll does do is to add to the substantial weight of evidence that the Yes side is well behind in the polls."

Er, come again? How does a poll which could easily be consistent with Yes being as high as 47% add to the weight of evidence that Yes is "well" behind? Or does a 47/53 split suddenly fit the definition of a "commanding" lead, to use Survation's recent word of choice?

In all honesty, though, I was shaking my head in disbelief looking through Survation's datasets. Respondents in the South of Scotland have been upweighted from 55 to 128, and over-65s have been upweighted from 95 to 232. The upweighting of young voters isn't quite so extreme this time, but it's still substantial. All of this introduces a level of randomness (and likely volatility) into Survation's results which just isn't satisfactory. I get the slight impression that the various upweightings may have slightly helped Yes on this occasion, but it's difficult to be sure given that it's a female-only poll. Yet again, the No lead is fractionally lower in the raw unweighted data than it is in the weighted numbers, but that's probably due in large part to the extreme shortage of older voters in the raw sample.

To the extent that we can take the results seriously, though, the good news is that the gap is slightly smaller on the unrounded numbers...

Should Scotland be an independent country? (Women only, Don't Knows excluded)

Yes 40.4% (+1.3)
No 59.6% (-1.3)

Undecided female voters were pressed on how they would be most likely to vote, and they split 48.7% Yes, 51.3% No (excluding respondents who still couldn't give a view). Because that's a much narrower gap than in the headline numbers, it means that the No lead would be slightly lower if 'undecided leaners' were added in. For technical reasons, it's not possible to make the calculation, but it would probably work out as either a 41/59 or 42/58 split (and based on Curtice's observation, that could easily be consistent with a Yes vote of as high as 48% once men are taken into account!).

One thing I should have pointed out last night is that Survation still haven't joined the new orthodoxy of weighting by country of birth, so for that reason they may well be understating the Yes vote slightly in all of their polls.