There are some fascinating findings in the new research from Edinburgh University which highlights voters' attitudes to risk and the independence referendum.

It is perhaps unsurprising that voting intentions appear linked to how concerned or otherwise people are about issues such as currency, future public spending and Scotland's prospects within the Union. It is not clear whether the 70 per cent of Yes voters who are confident Scotland will be able to keep the pound support independence because they believe this, or believe it because they have decided to vote Yes.

Likewise, it is not clear if No voters who are certain the UK Government will not cut Scottish public spending after the referendum actually believe this or are rationalising their voting intention based on an act of faith.

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But one of the points shown clearly by this study is that voters accept that neither side in the independence debate really knows the answers. That is a rational stance. One of the frustrations of the debate for voters, politicians and commentators alike has been the lack of decisive answers about key risks.

The Yes campaign has been particularly afflicted by this. The uncertainties attached to an independence vote have been played on by their opponents, while risk-averse members of the public have expressed concern that they cannot get the information they want. This is plainly seen in debates about the future currency of an independent Scotland.

The No campaign has not had to defend its position in the same way, as researchers point out. The study says voters generally attach greater weight to fears associated with independence than those relating to the continued Union.

Researchers were also struck that fears about negative outcomes had more effect on voting intentions than possible benefits of either result.

But there are unanswered questions on both sides. One key unknown is whether the UK will remain in the EU if David Cameron gets to honour his pledge to hold an in-out referendum.

This depends on the result of next year's General Election, which is also plainly in the balance as a YouGov poll showing the Conservatives drawing level with Labour demonstrates.

Even more important is the question of greater powers for Scotland after a No vote. All the parties have pledged them, but their offerings differ. The majority of the electorate want more powers for Scotland but if someone votes No, they do not know who will deliver what, or when.

Some, perhaps most, of these imponderables cannot be decisively answered and it is unfair to expect that they will. Is voting No inherently "safer"? Only if it is seen as a vote for no change, but it is not that. Further significant change is coming for Scotland, including a possible exit from the EU.

Yes supporters are often accused of voting with their hearts, not their heads. But a No vote can equally be cast in these terms. Voters understand the risks and are wary of either side promising certainty. There is a limit to what can be predicted and neither side has a crystal ball. That is certain.