正如经济学家尼古拉斯·卡尔多（Nicholas Kaldor）在很早以前指出的那样，由于制造业比服务业的规模收益更高，制造业出口商往往会比服务出口商表现更佳。
As the economist Nicholas Kaldor pointed out long ago, because manufacturing has higher returns to scale than services, manufacturing exporters tend to beat service exporters.