William Dickens, however, is not one of them. “I have a lot of problems with that.”

Dickens is a distinguished professor of economics at Northeastern University in Boston, who has written and researched extensively into the causes and effects of unemployment. “Before the recession, (full employment) was typically estimated to be in the range of 4 to 6%. Since the recession, there are indications that number may have gone up. My own estimates suggest it is somewhere between 5 and perhaps a little bit over 6% now, although nowhere near 7 or 7½%.”

The ways in which those numbers can change are complicated. Imagine a chalkboard filled with elaborate, baffling equations and you’ll get the gist even if you don’t get the picture.