Methods of controlling olefin polymerization reactor systems may include a) selecting n input variables, each input variable corresponding to a process condition for an olefin polymerization process; b) identifying m response variables corresponding to a measurable polymer property; c) adjusting one of more of the n input variables using the olefin polymerization reactor system and measuring each of the m response variables as a function of the input variables for olefin polymers; d) analyzing the change in each of the response variables as a function of the input variables to determine coefficients; e) calculating a Response Surface Model (RSM) for each response variable determined in step d); f) applying n selected input variables to the calculated RSM to predict one or more of m target response variables; and g) using the n selected input variables to operate the olefin polymerization reactor system and provide a polyolefin product.