A linkage between two things is a link or connection between them. The linkage of two things is the act of linking or connecting them. 联系
noun [专属名词] 联系；（国与国之间达成的）互换约定；连接，接合；链条，连接环节；基因连锁（同一染色体上的基因组一起被遗传的特性）
No one disputes the direct linkage between the unemployment rate and crime. 谁都不会质疑失业率与犯罪之间的直接联系。
