The task of trying to predict the behavior of productivity in the medium-to-long run is complicated by the fact that productivity growth generally varies with the business cycle, tending to be below its longer-term trend when the economy is contracting and above that trend when the economy is in the early stages of an expansion (see Basu and Fernald, 2001, for a discussion).
Monetary policies to combat the crisis  When the crisis became acute the initial response of most central banks took the form of rapidly executed reduction in the policy interest rate. When the policy rates reached an effective lower bound, central banks had to resort to unconventional policies. Though details of these policies differ, one can classify them in two main types.