1. A computer implemented method of controlling a manufacturing process, comprising the steps of: a.) during operation of the process, measuring the process with sensors of data representative of a plurality of process/product variables; b.) in a computer, connected to receive data from the sensors using multivariate analysis, said computer generating a surrogate variable having a value representative of whether or not the process is in control, said surrogate variable being a function of a plurality of intermediate variables, each of said intermediate variables being a weighted function of the process/product variables; c.) when the value of the surrogate variable is outside a predetermined limit, said computer determining which of the intermediate variables primarily contributed to the value of the surrogate variable; d.) for the intermediate variable determined in the previous step, identifying which of the process variables primarily contributed to the value of the determined intermediate variable; and e.) said computer modifying the process to change the process variable identified in the previous step to bring the value of the surrogate variable within the predetermined limit.