Abstract
It is pointed out that, when the coherent potential approximation is extended to the case of liquid metals by applying the Yonezawa method (1964) for the selfcontained treatment of multiple occupancy corrections in determining the selfconsistent equations for the average Green function and the self energy, the results reduce to the effective medium theory proposed by Roth (1972-4). The approximations involved in this and several previous theories are clarified by means of diagrams in the tight binding representation.