A lithographic apparatus is disclosed. The lithographic apparatus includes a scatterometer configured to measure a property of the substrate. The scatterometer includes a radiation source configured to produce a radiated spot on a target on the substrate, where the radiated spot includes positions on the target. The scatterometer further includes a detector configured to generate measurement signals that correspond to respective ones of the positions of the radiated spot and a processor configured to output, based on the measurement signals, a single value that is representative of the property of the substrate.