问答题

Amid the hubbub over a few less-bad-than-expected statistics, America’s economic debate has turned to the nature of the recovery. Optimists expect a vigorous rebound as confidence returns, pent-up demand is unleashed and massive government stimulus takes effect. Most observers are bracing for a long slog, as debt-laden consumers rebuild their savings, output growth remains weak and unemployment continues to rise. There is, however, something that eventually will have a much bigger impact on America’s prosperity than the slope of the recovery. That is the effect of the crisis on America’s potential rate of growth itself.
An economy’s long-term speed limit (its "trend" or "potential" rate of growth) is the pace at which GDP can expand without affecting unemployment and, hence, inflation. It is determined by growth in the supply of labor along with the speed with which productivity improves. The pace of potential growth helps determine the sustainahility of everything from public debt to the prices of shares. Unfortunately, the outlook for America’s potential growth rate was darkening long before the financial crisis hit. The IT-induced productivity revolution, which sent potential output soaring at the end of the 1990s, has waned. More important, America’ s labor supply is growing more slowly as the population ages, the share of women working has leveled off and that of students who work has fallen.