It is not a fact the Scottish Government has been particularly keen to publicise but now we know:

an independent Scotland would borrow billions of pounds in the first few years after leaving the United Kingdom in an attempt to kickstart the economy. The Chancellor George Osborne plans to limit increases in public spending to one per cent per year, but in the first three years of independence the Scottish Government would increase spending by three per cent each year and pay for it by borrowing more. In 2018/19 alone, this would mean extra borrowing of £2.4 billion.

In an interview with The Herald, the Finance Secretary John Swinney has tried to explain the reasoning for the extra borrowing. The money would be used, he says, to encourage continued recovery; it would be borrowing, in Mr Swinney's words, to boost growth and economic dynamism. The three main planks of the strategy would be increased productivity, a rise in employment and more immigration.

In theory, the strategy has its appeal and may attract the support of voters who are swithering about which way to go in the referendum, particularly Labour voters who are frustrated by what they see as a failure of the Labour leadership to offer an alternative to austerity.

However, there is a lack of detail in the plans. The increased borrowing was implied in the recent SNP report that argued Scots would be £1,000 better off after 15 years of independence, but exactly how the borrowed money would be spent is unclear. One fair bet might be big infrastructure projects, another might be research and development, but the returns are by nature unpredictable (although Mr Swinney would argue control over the tax system would allow him to offer incentives to foreign investors that could help things along).

What will certainly affect the outcome is the credit rating Scotland would attract and, on this, the omens are not good. Mr Swinney dismisses the idea an independent Scotland would be given an inferior rating but the experts, including the ratings agencies themselves, are lined up against him. He says the Scottish Government has proved it can balance the books, but would Scotland attract the top rating when there is likely to be so much uncertainty over the financial arrangements in a new state?

If it did not attract the top rating (and there has to be the prospect of that happening), the borrowing Mr Swinney plans would cost even more and take longer to pay off.

On immigration and employment, the Scottish Government is on much firmer ground. Employment is already heading in the right direction, although youth unemployment is proving hard to shift. It is also clear that Scotland does need more immigration and the target of 24,000 a year is not unachievable if the Scottish Government goes ahead with its plan for a points-based system based on the Australian model; it could also encourage more students to come to Scotland by changing the rules on visas. The idea that ex-pats would come flooding back in the wave of post-independence euphoria seems much more like wishful thinking.

What underlines all of these factors is that there are no guarantees; indeed, the plan for extra borrowing introduces uncertainty into other elements of the SNP's plans. Where would extra borrowing leave an oil fund, for example? The SNP says not to worry; the extra borrowing will get the economy off to a flying start in the first few years and the deficit will fall. Perhaps. Perhaps not. The prospects for success are just another of the economic factors voters will have to weigh up.