Abstract This article focuses on a study which showed the implicit assumptions in mix and yield variance analysis. A mix situation may exist whenever more than one direct material is specified as an input of the standardized operations. Mix variance can be described in two ways: (a) the sum of individual actual quantities times the individual standard unit prices less the sum of actual quantities at the weighted average standard price (based on standard quantities and mix) or (b) the sum of actual quantities times individual standard prices less the computed normalized mix quantities at individual standard prices. The normalized mix quantities are computed for each material by applying the standard proportions for each to the total actual inputs defined in quantity terms. A necessary condition then for the analysis of mix and yield variances, by the methods described, is the establishment of a common unit of measurement of the quantities of the different material inputs.