Pollsters nervous despite indications that Scotland will spurn independence
Opinion polls, financial markets and bookmakers are unanimous - Scotland will reject independence in a historic referendum next month and the United Kingdom will endure.
But what if, as Scottish nationalists believe, the polls are wrong - and the recent momentum towards a 'Yes' vote upsets the odds? Experts say it is a possibility.
The September 18 vote, the first of its kind in British history, has thrown up unique circumstances which make forecasting the outcome unusually difficult. Surveys are consistent on trends but diverge when it comes to the size of the gap between the two campaigns.
Few are ready to exclude an upset.
"Pollsters are particularly nervous given the disparity between them," John Curtice, a professor at Strathclyde University and a leading authority on polling, said.
"Some of the polls are definitely wrong because they don't agree. We just don't know which ones yet. This is a pretty tough call for the polling industry."
Pollsters recall 2011 and a major political shock when the pro-independence Scottish National Party confounded expectations to win a majority in the Scottish parliament.
Pollsters are also haunted by the occasions when they called UK general elections spectacularly wrong - in 1970 and 1992.
Yet the current picture, if averaged out, looks unambiguous.
The most recent 'poll of polls', on August 15, based on an average of the last six polls and excluding undecided respondents, put support for independence at 43pc against 57pc for staying in the UK, a hefty 14-point gap.
And only one poll in the last year, in August 2013, gave the pro-independence campaign a lead over the anti-independence side (by a slender 1pc). The validity of that survey, regarded as an outlier, was questioned by some experts.
There is a wrinkle, though. The campaign's six pollsters have come up with sharply different estimates of the gap separating the two camps, ranging from three to 32 percentage points in the last year. And the most recent poll, by Survation, showed the No camp's reduced from 13 points to just six.
The polls also differ widely on the number of undecided voters - from 7pc to 33pc.
Such variations raise awkward questions about who is right.
If the pollsters who say the gap is slimmer and the number of undecideds is higher are correct, there is more scope for volatility. A relatively modest swing to 'Yes' in an electorate of four million voters could be significant - particularly given the turnout is forecast to be as high as 80pc. But for now, equanimity prevails.
Apart from a glimmer of turbulence in currency markets, there is scant evidence that financial markets expect a shock.
Many still see it as too remote a possibility to worry about. Others say even the volatility caused by a 'Yes' vote would not be enough to justify the cost and complexity of insuring their positions against it. (Reuters)