1. A method of evaluating the adequacy of a profile model of a wafer structure to be used for process control of a fabrication process to fabricate the wafer structure, the profile model including profile model parameters, the method comprising: a) selecting one or more types of process control to be used in controlling the fabrication process; b) selecting one or more profile model parameters to be measured in implementing the one or more selected types of process control; c) setting an acceptable range for each of the selected one or more profile model parameters; d) selecting a first metrology tool to be used in measuring the one or more selected profile model parameters of the wafer structure during the fabrication process; e) selecting a second metrology tool used to calibrate the first metrology tool; f) setting one or more statistical metric criteria that define an acceptable amount of variation in measurements obtained using the first metrology tool and the second metrology tool; g) selecting a profile model to be used with the first metrology tool; h) obtaining a measurement of the one or more profile model parameters using the first metrology tool and the selected profile model; i) obtaining a measurement of the one or more profile model parameters using the second metrology tool; j) calculating the one or more statistical metric criteria based on the measurements of the one or more profile model parameters obtained using the first and second metrology tools; k) comparing the one or more calculated statistical metric criteria to the one or more set statistical metric criteria to evaluate the adequacy of the selected profile model.