One of the more persistent trends in the United States' postwar economic history is that the volatility in the performance of the economy has decreased over time. For example, from 1948 through 1969, the median change in the real GDP growth rate from one quarter to the next was 4.0 percent. Since 1987, however, it has been just 1.8 percent. A similar, although slightly less dramatic trend can be observed in the behavior of the unemployment rate. The economy, over time, has become increasingly sticky, stubborn, robust, stable, or whatever synonym you prefer. It has more inertial momentum than it once did.

Decreased volatility -- momentum -- is generally thought of as a Good Thing. And it is a Good Thing -- if the economy is expanding. Right now, however, the economy is not expanding -- it is contracting. And when the economy is contracting, reduced volatility may be an altogether different thing. It may mean that contractions are longer as well.