The first involves the thrust and resilience of domestic demand
The second uncertainty pertains to the economic situation abroad.. Brexit could have signficant economic repercussions
A third key uncertainty for the U.S. economy is the outlook for productivity growth--that is, increases in the amount of output produced per hour worked. Productivity growth is a key determinant of improvements in living standards.
A fourth important uncertainty for the economic outlook involves how quickly inflation will move back to 2 percent.