Mediated class relations and method calls as a confounding factor on coupling and cohesion metrics to assess the fault proneness of object oriented software is evaluated and proposed new cohesion and coupling metrics labeled as mediated cohesion (MCH) and mediated coupling (MCO) proposed. These measures differ from the majority of established metrics in two respects: they reflect the degree to which entities are coupled or resemble each other, and they take account of mediated relations in couplings or similarities. An empirical comparison of the new measures with eight established metrics is described. The new measures are shown to be consistently superior at measure the fault proneness.