(Related to the Apply the Concept on page 841) In early 2009, Christina Romer,
who was then the chair of the Council of Economic Advisers, and Jared
Bernstein, who was then an economic adviser to Vice President Joseph Biden,
forecast how long they expected it would take for real GDP to return to
potential GDP, assuming that Congress passed fiscal policy legislation
proposed by President Obama:
It should be understood that all of the estimates presented in this memo are
subject to significant margins of error. There is the obvious uncertainty that
comes from modeling a hypothetical package rather than the final legislation
passed by the Congress. But there is the more fundamental uncertainty that
comes with any estimate of the effects of a program. Our estimates of economic
relationships ... are derived from historical experience and so will not apply
exactly in any given episode. Furthermore, the uncertainty is surely higher
than normal now because the current recession is unusual both in its
fundamental causes and its severity. Why would the causes of a recession and
its severity affect the accuracy of forecasts of when the economy would return
to potential GDP?