Two more measurements are made on the same workpiece, during fabrication. Each measurement may be made employing a different process. The measurements are used together to determine a property of the workpiece. For example, multiple measurements from a first process are used with a predetermined value of the property of interest in a simulator to generate a simulated value of a signal to be measured in a second process. One or more such simulated values and a measured value are used to identify a value of the property of interest. When the workpiece's property is found to not match the specification, a process control parameter used in the workpiece's fabrication is adjusted, thereby to implement process control.