In one embodiment, a method is provided for analyzing a circuit design. For each sub-circuit of a plurality of sub-circuits specified in the circuit design, a logic level probability is determined for each output of the sub-circuit. The logic level probability indicates the probability that an output of the sub-circuit will have a first value in response to possible values of inputs to the sub-circuit. Each logic level probability is converted to a switching probability that indicates a probability that a switching event will occur at the respective output of the sub-circuit within a time period. The switching probability is stored in a memory.