The equilibrium morphologies of different core-shell latices are predicted, and a related sensitivity analysis is given for the predictions. This article proposes a related sensitivity range for estimating the accuracy of predictions, made with the simple method, of the thermodynamically preferred morphology of a core-shell latex particle in two-stage seeded emulsion polymerization. The related sensitivity range of the predictions is defined and calculated, and the results show that different core-shell latices have different sensitivity ranges. The wider the sensitivity range is, the more reliable the prediction is of the morphology of the core-shell latex. The simple method of related sensitivity range has been verified in the literature and with experiments. (C) 2004 Wiley Periodicals, Inc.