"At a quick glance it looks like a London job adds almost exactly three times as much value to the UK economy as a whole as a South Scotland job. And let's be honest, a quick glance is often taken as plenty to dismiss the economics of independence in the media. But there is a problem, which is that the 'agglomeration effect' is measured without any reference to the many other factors which influence GVA. The Sheffield University report strips those factors out one by one to assess what like-for-like productivity would be."
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