1. A system operative to simulate robustness of a circuit module containing elements, a processor: a component, running on the processor, that conveys an expected distribution of global values associated the with elements of the module; a component that conveys an expected distribution of local values associated with elements of the module; and a modeling component that models behavior of the module and generates an output indicative of the robustness of the circuit module to random local variations of the elements for a chosen range of substantially uniform global variations of the elements, in response to the global values and the local values; wherein the random local variations affect each of the elements differently throughout the module, while the substantially uniform global variations affect the each of the elements substantially uniformly throughout the module.