Now the Don’t Knows Have It! New TNS-BMRB Poll

What a week! And it is only half over! On Sunday YouGov told us that Scotland was swinging towards No. On Monday Panelbase advised us that the country was swinging decisively in the Yes camp’s direction.  And, now, what do we learn today from TNS-BMRB? – that far from swinging either Yes or No Scotland is in fact caught in the grip of growing indecision. ‘Pollster, heal thyself’ might well be many people’s reaction.

According to TNS-BMRB’s poll published today, as many as 28% say they do not know how they will vote in the referendum. That represents a nine point increase in the ‘Don’t Knows’ as compared with TNS’s previous poll in the spring, and no less than a 13 point increase on the figure they recorded when last February they first asked people how they would vote in response to the referendum question.ngus Reid

 TNS themselves suggest that perhaps the increase has arisen because the two campaigns have been more effective at casting doubt on their opponents’ case than in convincing people of their own. However, no other recent poll has found the same trend – both Angus Reid (19% Don’t Knows or Won’t Votes) and YouGov (12%) found little or no change in the level of Don’t Knows, while in the SNP/Panelbase poll (13%) it was actually a little lower than in the same company’s previous poll for The Sunday Times (17%).

There are perhaps a couple of possible explanations for the divergence. The first relates to differences in how the polls were conducted.. All of the other recent polls were conducted over the internet with people who have volunteered to fill in that company’s surveys when asked, whereas TNS’s was conducted by knocking on people’s doors and persuading them to take part. Unsurprisingly the latter approach tends to be more successful at securing the participation of those with little or no interest in politics.  And in line with that pattern, whereas Panelbase found that 76% of their sample said they were certain to vote in the referendum, TNS estimate the proportion at just 62%. Perhaps what TNS have identified that the other polls have not is a growing disenchantment with the two campaigns that is concentrated specifically amongst those who are not political anoraks. Still, if and until there is some supporting evidence for TNS’s finding we should probably suspend our judgement on the issue.

The second and perhaps more likely explanation lies in a change that TNS have made in the introduction to their question on referendum voting intention. Hitherto, they have asked people, ‘If this referendum were to be held tomorrow, how would you vote…’. This time, however, they asked, ‘How do you intend to vote…’. The new formulation invites people to forecast what they will do in a year’s time rather than what they would do now, and perhaps we should not be surprised that rather more people are less certain about the former than the latter.

Either way, given the increase in Don’t Knows, the TNS poll inevitably provides little consolation to either the Yes or the No campaign. At 47%, support for the No side is down four points on its poll in the spring, while at 25% that for Yes is down just slightly more, five points. However, after the euphoria of the SNP/Panelbase poll it is the Yes side that will probably be the more disappointed with the finding, especially given that when compared with TNS’s February poll, the Yes vote is down by eight points but the No vote by only five.

Still, here perhaps we should enter another small word of caution. Unlike either YouGov or Panelbase, TNS do not weight their results so that their respondents’ reports of how they voted at the last election (the 2010 UK election in the case of YouGov, the 2011 Holyrood contest in Panelbase’s case) more or less match the actual outcome of that election. However TNS did actually ask their sample how they voted in 2011 – and found that rather fewer said they voted SNP than indicated they backed Labour. Such a divergence from what actually happened in 2011 is bound to raise questions about whether TNS’s sample adequately reflects the nation’s political balance.

Still, leaving all caveats and qualifications asides, what sense, if any, can be made of the flurry of polls published in the last fortnight? If we take out the Don’t Knows and Won’t Says, and then calculate the average Yes and No vote across all four, we find that No are ahead by 60% to 40%. If we undertake the same calculation for the last time each of the four companies in question (Angus Reid, Panelbase, TNS and YouGov) polled on the referendum the result is – yes, you have guessed it – 60% No, 40% Yes. The polls may be volatile but perhaps Scotland itself still remains largely unmoved by it all?

Topics: Referendum voting intention

About the author

John Curtice is Professor of Politics at Strathclyde University, Research Consultant to ScotCen, and Chief Commentator on the What Scotland Thinks website.