LONDON (Reuters) - Support for and against Scottish independence is running neck-and-neck a week before referendum day, leaving it to a sizeable number of undecided voters to tip the balance.
A series of opinion polls over the past week, with one notable exception, have shown a surge in support for the “Yes” campaign that has panicked Britain’s elite.
The recent poll movements mirror what happened in the run-up to the 1995 referendum in Quebec - one of the few obvious parallels in recent history - where voters opted to remain in Canada by a margin of just over 1 percent of votes cast.
Given what happened in Quebec, the late shift in momentum behind the Yes campaign in Scotland is not surprising, said Darrell Bricker, chief executive of Ipsos Public Affairs in Toronto.
While the “Non” side was comfortably ahead by nearly 10 percentage points two months before that referendum, the Yes vote surged ahead in six successive polls over a fortnight just ahead of the vote predicting a victory for “Oui.”
So far only one poll, from YouGov last weekend, has put the Scottish Yes vote in front, by just two percentage points in a survey with a margin of error of plus or minus two to three percentage points.
The latest poll released on Wednesday by Survation showed steady support for Yes (47 percent) and No (53 percent). But that excludes the 10 percent who said they are still making up their minds.
The sudden narrowing of the No lead from double digits to nil in other polls was enough to trigger selling in sterling markets on fears the UK might break up, and a race by the No campaign to spell out further devolution of powers to Scotland.
Asked whether or not independence will make their own or Scotland’s financial position any better, the latest YouGov poll shows very mixed opinions.
Among those aged 25-39, there is an even split between those who think they would be better off, worse off, no different or not sure of the personal financial impact of separation.
What is even more difficult to quantify is how many voters who tell pollsters they will vote Yes - because it is the bold and optimistic decision - end up voting the other way when they step into the privacy of the ballot box.
“Change is hard. If people perceive change as being risky, the status quo prevails ... (because) there tend to be ‘shy No’ voters,” said Bricker. “That’s what happened in Quebec.”
That is also a phenomenon noticed by pollsters in Britain during Margaret Thatcher’s reign when many voters were loath to voice support for her but often backed her at election time.
An academic study from 1999, “The Polls and the 1995 Quebec Referendum”, suggests that as one explanation for the outcome.
“Given the heated atmosphere of the referendum campaign, voters who opposed independence may have been differentially disposed not to respond to polls, and, when they did respond, may have misreported their voting intentions,” wrote John Fox, Robert Anderson and Joseph Dubonnet in a paper for the Canadian Journal of Sociology.
In an e-mail exchange, Fox, professor of sociology at McMaster University in Hamilton, Ontario, cautioned not to draw strong conclusions based on a single prior event.
But there are similarities, right down to the number of people who will vote and the proportion of undecided voters.
“The media at the time didn’t notice that the sampling error of the aggregated polls was much smaller than the sampling error of individual polls,” Fox wrote in an e-mail exchange.
The latest poll of polls provided by the non-partisan website "What Scotland Thinks" (here) shows the No side still ahead on 52 percent and Yes on 48 percent. This figure, like headline figures in individual polls, excludes the undecideds.
In the 1995 Quebec referendum, turnout was 93.5 percent, a little higher than the expected outcome in Scotland, at least based on the latest polls.
According to recent YouGov, TNS and Panelbase surveys, those declaring themselves most likely to vote are over the age of 60, with voting intentions close to or above 90 percent.
As women and opposition Labour party supporters have peeled away, the elderly are the only group that remains staunchly in the No camp, and by a considerable margin. As an age group, they also have the clearest opinions on what a Yes vote would mean for them and Scotland financially.
But younger voters, who say they are more inclined to vote Yes, including teenagers, are catching up and are telling pollsters they are likely to turn up in high numbers.
“The biggest thing I’d be looking at in any of the polling is likelihood of turnout,” said Ipsos’ Bricker.
TNS reported in its latest poll that Yes and No support is now tied at 41 percent - a significant shift from 46 percent No and 38 percent Yes in August with the number of undecideds at 18 percent among those who intend to vote.
Alastair Graham, research manager at TNS, said some people may have come late to the debate about what is at stake and are only now declaring themselves to pollsters as certain but undecided voters.
“Based on anecdotal evidence and speaking to people, you do get the impression there is a high level of undecideds out there,” said Graham, whose firm is one of the few which conduct face to face interviews with voters.
TNS and the last two YouGov polls have clearly tracked a leap in support for the Yes campaign since Scottish National Party leader Alex Salmond was perceived to have defeated “Better Together” leader Alistair Darling in a second televised debate.
The latest poll from Panelbase, taken over the same period, has not moved as much, with 48 percent declaring themselves No voters, up 2 percentage points. The Yes side also rose 2 percentage points to 44 percent.
Perhaps more striking is a finding from the TNS poll asking respondents which side they expect to win, regardless of how they intend to vote. The No side is ahead by 14 percentage points at 45 percent versus 31 percent for Yes, with nearly a quarter saying they don’t know.
That, too, could play into voter behavior. Polls showing a very close race could make people who intended to vote Yes on the expectation that the status quo will prevail think twice about the risk.
Responses to the latest Survation poll released on Wednesday, which showed the same gap between Yes and No as two months ago, were taken mostly after YouGov published its poll showing the Yes vote ahead for the first time.
With only a week to go, pollsters say voters tend to use this stage to fill in gaps in the information they need to take a careful decision at the ballot box.
The latest TNS poll shows about a fifth of respondents said they don’t yet know enough to take a decision.
“There’s still a lot of time. It’s now at the point where people are going to be looking around for objective commentary from people who don’t have an axe to grind,” said Bricker.
“The people whose hearts are in Scotland but whose heads are in the United Kingdom - these are the people who will decide the outcome.”
Editing by Anna Willard