State of the Debate: The Polls

Published: 11 September 2014
Author: John Curtice

John Curtice discusses the most recent polls and how in the final week of the campaign we may secure a clearer and more consistent picture of just where the referendum race stands.

The last ten days have transformed perceptions of the referendum race. Although they persistently and consistently disagreed about the size of its lead, every independently commissioned poll had hitherto put No ahead. Few expected anything other than a majority vote to stay in the Union.

However, this widespread expectation began to be eroded on Tuesday of last week when YouGov reported that the Yes vote now stood at 47%, just three points short of what is required for victory. True, this was far from being the first poll to suggest the race was that close, but because it came from one of the companies that had hitherto always put No well ahead, many a media commentator sat up and take notice.

However, the race really became electrified when on Sunday the findings of yet another YouGov poll were released. This showed that Yes were on 51% and No on 49%, making it the first independent poll to put the Yes side ahead. For the first time it seemed that there was a real possibility that Scotland might vote to leave the UK after all.

But YouGov’s poll was not the only one to be released on Sunday. There was also a poll from Panelbase, one of the pollsters that has long suggested that in fact that the referendum race might be quite close. Indeed, this latest poll repeated that message. But in putting Yes at 48% and No at 52%, it was also suggesting that Yes support was no higher now than it had been as long ago as June. Perhaps the swing in YouGov’s polls was in fact a bit of an anomaly.

Two days later, the existence of the swing identified by YouGov appeared to be confirmed when TNS BMRB, another company that had hitherto also suggested that No were well ahead, reported that now the Yes and No sides were evenly tied on 50% each. That result impelled all three Westminster party leaders to abandon the House of Commons and fly north to ‘save the Union’. A gloriously sunny Calton Hill in Edinburgh hosted the kind of media frenzy that is normally only seen outside the House of Commons on College Green.

On Tuesday night, however, there was another twist in the tale, this time from another pollster that has tended to paint a relatively optimistic picture for the Yes side, Survation. It suggested the result was close - Yes 47%, No 53% - but like Panelbase again no closer than it had already been as long ago as June. The swing had disappeared again.

So what are we make of this apparent confusion?

First we should note that all four of the most recent polls represent an all time high for the Yes side; it is just that in two cases the Yes side had already been that high before. That implies the Yes vote must be at least as high as it has been at any point during the campaign.

Second, after persistently disagreeing with each other we may finally be witnessing something of a convergence between the polls – but on the picture that suggests the referendum race is tight, though with the No side still marginally ahead. The poll of polls on the website, based on the six most recently conducted polls, now stands at Yes 48%, No 52%, the smallest lead for No it has ever recorded.

Third, we perhaps should not be entirely surprised that if there has been some swing to Yes, those polls that have hitherto painted a relatively pessimistic picture for the Yes side proved better able to detect it. After all, because the Yes vote was relatively low in these polls beforehand, there was more opportunity for it to advance. Conversely, those polls that already been suggesting that Yes were riding relatively high were at greater risk of missing any swing.  And if the polls have finally begun to converge, then perhaps in the final week of the campaign we will secure a clearer and more consistent picture of just where the referendum race stands than we have enjoyed at any time in this long if now nerve-tingling campaign.

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