Eric Rauchway had a great article on this. on how unemployment was measured differently to how it was in Germany for example.
Now I am late on this but it makes for interesting reading.
If only Gerry Jackson was in good health it would make for a great debate.
It further backs up my theory that if Roosevelt had a policy of real wage reductions as advocated by Keynes ( inflation illusion) then the US recovery would have been comparable to Germany's recovery.