An apparatus includes a plurality of die areas having integrated circuit (IC) die each having circuit elements for performing a circuit function, and scribe line areas between the die areas. At least one test module is formed in the scribe line areas. The test module includes a reference layout that includes at least one active reference MOS transistor that has a reference spacing value for each of a plurality of context dependent effect parameters, and a plurality of variant layouts. Each variant layout provides at least one active variant MOS transistor that provides a variation with respect to the reference spacing values for at least one of the plurality of context dependent effect parameters.