With all bets off in the run-up to the referendum, New-Keynesian Paul Krugman has added his opinion to the mix.
I have a message for the Scots: Be afraid, be very afraid. The risks of going it alone are huge. You may think that Scotland can become another Canada, but it’s all too likely that it would end up becoming Spain without the sunshine.
Krugman goes on to claim that Scotland, despite perhaps seeing itself as Canada - a small economy trading predominantly with a larger neighbour - is more like Spain.
Canada, Krugman says, has its own currency and that "makes a big difference".
He goes on to say Canada, despite its prosperity, probably suffers despite a free-trade agreement with the States.
All these points are not new and have been the subject of much debate.
Meanwhile, back in the UK, politicians have made the decision to fly the Scottish flag over Downing Street and Whitehall until the referendum on 18 September, and earlier Cameron, Miliband and Clegg announced they would be skipping PMQs tomorrow to campaign in Scotland.
In a joint statement Cameron, Clegg and Miliband declared:
There is a lot that divides us – but there's one thing on which we agree passionately: the United Kingdom is better together.That's why all of us are agreed the right place for us to be tomorrow is in Scotland, not at prime minister's questions in Westminster.We want to be listening and talking to voters about the huge choice they face. Our message to the Scottish people will be simple: we want you to stay.