Have the Sunday Herald just totally misrepresented John Curtice's stance on so-called "tactical voting"?

And the nonsense about "tactical voting on the list" just goes on and on and on.  The SNP have got every right to be extremely annoyed about a piece in today's Sunday Herald, which makes the wildly implausible claim that Professor John Curtice has told independence supporters that they shouldn't vote for the SNP on the list, because that would "let unionist MSPs in by the back door".  I can't actually locate the Electoral Reform Society report in which he's meant to have said this, but I'm going to very confidently predict that when it does turn up, we'll find that the actual text is markedly different to the spin the Sunday Herald have put on it.  We know that Curtice's supposed "advice" simply doesn't tally up with observations he's made extremely recently, and indeed with basic indisputable facts that any psephologist will confirm.

What seems to have happened is that Curtice has averaged recent opinion polls, and found that if those figures were reproduced in the election in May, the SNP would win all but three of the constituency seats, and only two of the list seats.  But here are the rather enormous "buts" that the Sunday Herald aren't bothering to tell you about -

1) An average of opinion polls conducted weeks or months before polling day is categorically NOT a prediction of the election result (the Sunday Herald piece specifically uses the inaccurate word "predicts"), but simply a snapshot of public opinion which is subject to change as the campaign progresses.  Curtice made that very point himself when he was asked by The National to give his verdict on the "tactical voting" issue a few weeks ago.

2) Opinion polls are not necessarily even 100% accurate as snapshots, and averaging them cannot be assumed to eliminate any error.  Curtice has confessed a number of times that he's learned to go into the BBC studio on general election night with no preconceptions, because the picture that unfolds is so often radically different from the pre-election polls.  Last year, the polls suggested a dead heat between Labour and Tory, but we ended up with a clear Tory victory.  In 2010, the polls suggested a Liberal Democrat breakthrough, but Nick Clegg actually suffered net losses.  In 2005, the polls suggested that Labour would have a majority of 100 or so, but the eventual number was 66.  You'd actually have to go back a full 15 years to get to a UK general election that didn't spring some kind of major surprise on the night.  The idea that opinion polls offer us precise foreknowledge of the exact number of constituency and list seats that the SNP will win next month is in the realms of fantasy.  At the absolute most, they can provide a vague ball-park figure with considerable scope for error.

3) Curtice has repeatedly pointed out that polling on the list has proved significantly less accurate in past Holyrood elections than constituency polling, and that we generally find that the SNP's list vote turns out to be much closer to their constituency vote than the pre-election polls have led us to expect.  Conversely, the Green list vote tends to be overstated by polls.  That puts a particularly big question mark over the credibility of any extrapolation of list seats based on current polls, and I'm quite sure Curtice will have gone out of his way to explain that in his report.  It's suspicious, for example, that the SNP apparently aren't pencilled in for a list seat in the North-east, because they currently hold a list seat there in spite of having won every single constituency seat in the region in 2011.  It'll be especially interesting to see how Curtice has dealt with the problem of Survation polls, because he's stated that Survation's results for the list ballot lack credibility due to the way the question is posed.

4) Extrapolations of constituency seats are also problematical, not least because we don't know in advance the extent of anti-SNP tactical voting in a handful of potentially close contests.

5) The phrase about "letting unionist MSPs in by the back door" (which unsurprisingly does not appear to be a direct quote from Curtice) makes very little sense, because it implies that a list vote for the SNP could somehow lead to more unionist MSPs being elected than the unionist vote would justify.  The complete opposite is the case - the tactic of switching to a smaller pro-independence party on the list is supposed to prevent the unionist parties from winning their proper entitlement of list seats.  If "letting unionists in by the back door" simply means "failing to cheat unionists out of winning their fair share", that's a very, very odd use of language at the very least.

6) To support the claim that SNP list votes might be "wasted", the Sunday Herald piece risibly prays in aid the fact that smaller parties need 5-6% of the vote in a region to win one seat.  How that's supposed to assist the argument for tactical voting is a complete mystery.  I have no doubt that Curtice himself will have made the more realistic point that the 5-6% de facto threshold means there is every danger that some "tactical" list votes for smaller parties will be completely wasted.  It's certainly going to be very difficult, bordering on impossible, for RISE to hit that target figure in even one region, let alone in eight.

I suspect that the report will turn out to be quite nuanced, with Curtice simply saying "if the election result reflects the average of recent opinion polls, SNP voters may wish they had switched to another party on some regional lists", but then going on explain that there are very good reasons for supposing that the figures he's referring to may not be the eventual result, and that it's therefore impossible to be sure in advance of the election that the proposed "tactical" voting strategies will not backfire.  That was essentially the balanced message he supplied to The National a few weeks ago, and as the basic facts haven't changed, I'm quite sure his verdict won't have changed either.  If he's been misrepresented as badly as I suspect he has, it'll be interesting to see his own reaction to the article - he's usually very mild-mannered, but he's surely not going to be best pleased about it.

UPDATE : In the comments section below, Topher has provided a link to Curtice's actual report.  You can read it HERE.  If anything, the Sunday Herald's misrepresentation is even worse than I suspected.  Their claim that Curtice advises independence supporters to vote RISE or Green on the list is not merely a distortion - it's flatly untrue.  He specifically states that voters face a "dilemma" because there are "risks" attached to tactical voting, and that it's understandable that the SNP are trying to avert those risks by sending out a "both votes SNP" message.

UPDATE II : I've got to be honest - I am absolutely dumbfounded to learn that the editor of the Sunday Herald seems to have spent most of the day insisting on Twitter that the article is 100% accurate, even though anyone can simply read the Curtice report online, and see for themselves that it differs radically from the way it was summarised in the article.  Even Curtice himself has indicated (with his characteristic understatement and diplomacy) that the wording of the article was a bit "strong" - and if he's not in a position to make that call, I don't know who is.  This is an open and shut case.

I don't think there's any conspiracy here - it was just a sloppy article written by someone who in all probability had genuinely misunderstood what Curtice had written (possibly with the help of a little misdirection from the Electoral Reform Society, who do have a pretty obvious agenda on this subject).  But if you've made an honest mistake, and it's blindingly obvious to everyone that you've made it, why would you dig your heels in and defend the indefensible for hours on end?  I really, really don't understand what's going on.