让我首先以第二次世界大战为界,把战前和战后美国经济的运行情况做个大致的比较。第一,从经济稳定性的比较来看:把三十年代大萧条时期排除在外(否则的话,与战后的种种比较会受到严重干扰),我们发现,战前经济每衰退1年大约可换得1年的扩展;而战后,则是每衰退1年大约可换得4年的扩展。与战后的衰退相比,1930年以前的衰退不仅时间长得多,而且衰退程度也严重得多;从有关增长趋势的标准差来看,战前此值是战后的 Let me first of all make a rough comparison of the operation of the U.S. economy before and after the war with World War II as the boundary. First, judging from the comparison of economic stability: the exclusion of the Great Depression in the 1930s (otherwise, the comparison with the post-war period would be severely disrupted), we find that the pre-war economy could be exchanged for about 1 year of recession A year of expansion; and postwar, an expansion of about four years for every one year of recession. Compared with the post-war recession, the pre-1930 recession was not only much longer, but also worse than the recession. From the standard deviation of the growth trend, the prewar value was post-war