Computing repair hints for litho hotspots is made more effective with a model of how Process Window contour bands changes as a function of design layout changes. We have developed a modeling methodology called pRSM (Partition Response Surface Model). In our approach, we create a family of models along with error bound estimate models. We first classify design layout configurations into a small number of partition categories and then build a RSM model and error bound model for each partition category. In this paper we describe our pRSM methodology and present results illustrating the advantages of our methodology over that of traditional RSM approaches.