摘要：In the past quarter century, the ups and
downs of the American economy — that is,
its business cycle volatility — have decreased.
That’s a good thing: it means less severe recessions,
milder swings in the unemployment
rate, and possibly fewer business failures. Over
the same time period, though, the volatility
of employment growth rates and sales growth
rates at some 10,000 companies whose securities
are traded on various stock markets have
risen, on average.
