A method is described for obtaining information for use in modeling of a lithographic process. A pattern feature is formed on a target portion of a substrate by projecting a beam of radiation onto the target portion of the substrate. For that target portion the lithographic process is characterized by one or both of a first property that varies in a first direction along a surface of the substrate, and a second property that varies in a second direction along a surface of the substrate. A property of the pattern feature is measured. Using the measured property of the pattern feature and at least one of the first and second properties, information is obtained for use in modeling the process. The lithographic process may be or include the projection of the beam of radiation onto the surface of the substrate.