This invention relates to a method for selecting a polyolefin having a die swell within a pre-selected range, the method comprising (a) obtaining from reference samples of a plurality of polyolefin batches a data set for at least one property, other than die swell, of the polyolefin; (b) obtaining a die swell data set from the reference samples of the polyolefin; (c) correlating the at least one property and the die swell data set using a regression analysis to generate an equation for predicting the die swell as a function of the at least one property from step (a); (d) obtaining from a non-reference polyolefin sample a value for each variable in the equation from step (c) and calculating the predicted die swell from the equation from step (c); (e) comparing the predicted die swell of step (d) to the die swell within the pre-selected range, and (f) rejecting the non-reference polyolefin when the predicted die swell for the non-reference polyolefin is outside of the pre-selected range of the die swell. This invention relates to the use of the method in the production of blow-molded articles and in the control of a polyolefin reactor process.