Can someone please explain to STV how debates are supposed to work?

Try to imagine a tennis umpire saying something like this -

"Advantage Djokovic.  Ladies and gentlemen, Mr Federer is challenging the call, on the left-hand baseline.  The ball was called out.

Call stands.  Advantage Djokovic.  Incidentally, ladies and gentlemen, I've just heard from the commentary box that John McEnroe feels that the Federer backhand is under severe pressure, and that the Swiss player has it all to do if he's not going to be broken in this game.  Word is also coming through from Ladbrokes that the odds on a Djokovic win have tightened since I announced that the Federer backhand is under pressure.  Play."

Or how about the moderator of a US presidential debate saying something like this -

"Each candidate will be allowed a two-minute introductory statement, and a three-minute closing statement.  I will also ensure that the time they receive to answer my questions is roughly equal.  We do have an audience present but they have agreed to remain silent.  Governor Romney won the toss and chose to make his introductory statement first, but before we go to him, let's have a look at our exclusive Gallup poll!  It shows that 57% of Americans feel that Governor Romney is smug, arrogant and out-of-touch.  Looks like you're fighting a losing battle here, Governor Romney, but feel free to give it a go anyway.  The floor's all yours."

Are you starting to see the point?  That would never happen in a million, zillion years, but what STV are planning for this evening isn't far short of such lunacy.  First of all, they shouldn't be starting a debate with a poll, full stop.  Debates are supposed to provide a neutral environment and an entirely level playing field for both sides to make their case, and for viewers to weigh up the arguments without the intrusion of extraneous factors.  It defeats the whole purpose if the debate's moderator informs viewers right at the outset that one side is "winning", and it self-evidently unbalances the playing-field.

But it's even worse that that, because this is a very unusual campaign in respect of the polling landscape.  In their leaders' debate at the start of the 2011 Holyrood campaign, STV did exactly the same thing (and as you can see here, I criticised them for it at the time), but at least their poll was reasonably representative of what all the pollsters were showing in that campaign.  The only real outlier in 2011 was YouGov, who were far too Labour-friendly.  But this time around, there is a huge disparity between different pollsters, and by choosing Ipsos-Mori - one of the two most No-friendly pollsters - STV are making a hugely political decision with huge political consequences.  They may not have admitted that to themselves, but that's the position.

To put it in perspective, the highest Yes vote that Ipsos-Mori have found at any point during this campaign is just 40%.  All but one of the firm's polls have put it below 40%.  Contrast that with ICM, Panelbase and Survation, all of whom at various times have put Yes as high as 47% or 48%.  Even YouGov and TNS-BMRB have had Yes as high as 42% and 44% respectively.  So if Bernard Ponsonby starts the debate by pointing to the poll and echoing his words of last night that "Alex Salmond has it all to do because No have a big poll lead", what he'll really mean is "Alex Salmond has it all to do IF our own house pollster is the most accurate, but nobody knows whether they are".  Will viewers realise that they're only being given half the story (if that)?  Some will, but most won't.

I should emphasise that it's a very good thing that STV commission polls - if they weren't doing it, we'd have no telephone polls at all in this campaign, which would be extremely unhealthy.  But there's a time and a place for everything, and the time and place for polls is in a news programme, not in a debate that is supposed to help people decide how they want to vote, as opposed to telling them how they are supposedly going to vote.

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One thing I'll be looking out for is the sample size of the Ipsos-Mori poll.  If it's a standard sample of 1000, it won't explain why we've heard so many people report that they've been interviewed by the firm recently, because that certainly hasn't happened during previous STV polls (but of course it did happen during the UK government-commissioned mega-polls).  I still have suspicions that there may have been more than one Ipsos-Mori poll in the field over the last few days - although if tonight's sample turns out to be 5000+, it would probably solve the mystery.