1. A method of analyzing impact of a rule on a layout, the method comprising: generating a variant of the layout for each of a plurality of values for the rule, resulting in a plurality of layout variants; determining, for each of the layout variants, a device metric value for a device metric, resulting in a plurality of device metric values; identifying a relationship between the rule and the device metric based on the plurality of device metric values; and graphically indicating, on a display device, the relationship between the rule and the device metric, wherein graphically indicating comprises defining a curve that defines the relationship between the plurality of values for the rule and the plurality of device metric values and that is displayed on the display device.