1. A method for monitoring a manufacturing process, comprising: a. acquiring metrology data for semiconductor wafers at the conclusion of a final process step for the manufacturing process; b. acquiring data for a plurality of process variables for a first process step for manufacturing semiconductor wafers; c. creating a first mathematical model of the first process step based on the metrology data and the acquired data for the plurality of process variables for the first process step; d. repeating step b. and step c. for at least a second process step for manufacturing the semiconductor wafers; e. creating an n th mathematical model based on the metrology data and the data for the plurality of process variables for each of the n process steps; and f. creating a top level mathematical model based on the metrology data and the models created by steps c., d. and e., the top level mathematical model being based on those process variables that have a substantial effect on the metrology data.