How bad is the US crisis -- a historical/comparative perspective?

Not as bad compared with economic crisis in other countries, but . . .

. . . deeply bad compared with the US historical record. 

Source. HT: Free Exchange

Two perspectives on the US macroeconomy

A demand side perspective (the problem is consumption, which might become a supply side problem).

A supply side perspective (the problem is TFP).

Robert Barro 1 - Paul Krugman 0

Greg Mankiw argues:

Paul's comment on Robert's latest column confuses me.  Paul shows a graph establishing that the investment share of GDP is procyclical, as if that refutes Robert's viewpoint about what ails the economy.  But that fact is hardly a surprise.  As I put it recently, "the most volatile component of G.D.P. over the business cycle is spending on investment goods."  Moreover, I know Robert well enough, having been his colleague for about a quarter century, to know that he knows the macroeconomic time series as well as anyone. Keep reading . . .