For example, estimates of long-term productivity growth are needed to determine the rate of output growth that the economy can sustain in the long run without generating inflationary pressures.
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).