For some years I have been writing about the phenomena of the twin secular stagnations (see here: http://trueeconomics.blogspot.com/2015/07/7615-secular-stagnation-double-threat.html). And just as long as I have been writing about it, there have been analysts disputing the view that the U.S. (and global) economy is in the midst of a structural growth slowdown.

A recent NBER paper (see here http://www.nber.org/papers/w23543) clearly confirms several sub-theses of the twin secular stagnations hypothesis, namely that the current slowdown is

1. Non-cyclical (extend to prior to the Global Financial Crisis);
2. Attributable to "the slow growth of total factor productivity"
3. And also attributable to "the decline in labor force participation".